Nelson Mandela has been at the forefront of the fight against Aids
Mandela urges action
The UN recently reduced its estimate of the number of people with HIV/Aids, but the figure still stands at 33 million.
Campaigners warn that better treatment has bred complacency about the risks.
"The trend is encouraging but still for every person receiving treatment four others are newly infected," said former South African President Nelson Mandela.
'Breaking the cycle'
Mr Mandela was speaking at a concert in Johannesburg, South Africa, where international musicians, including Annie Lennox and Peter Gabriel, were performing alongside local talent.
"If we are to stop the Aids epidemic from expanding, we need to break the cycle of new HIV infections. All of us working together with government, communities and civil society can make the difference that is needed," he added.
The concert is the latest event organised by the 46664 campaign - which is named after Mr Mandela's old prison number and began five years ago.
South Africa has more HIV infections than any other country - five million South Africans are HIV positive.
After years in which the South African government was accused of "Aids denial", the country now has the world's largest programme of antiretroviral treatment.
But Aids campaigners say more must still be done - especially in preventing mother-to-child HIV transmission.
And I call for leadership at all levels to scale up towards universal access to HIV prevention, treatment, care and support by 2010
Ban Ki-moon
UN Secretary General
Fears over homeopathy role
UN chief Ban Ki-moon said strong leadership was needed if the fight against the disease was to be won.
And he called for renewed efforts to focus on helping women, who now make up half of those living with Aids worldwide, and for better funding for prevention and care programmes.
"I call for leadership among all governments in fully understanding the epidemic - so that resources go where they are most needed," he said in a speech in New York.
"And I call for leadership at all levels to scale up towards universal access to HIV prevention, treatment, care and support by 2010," he added.
US fund increase
US President George W Bush on Friday urged the US Congress to authorise the doubling of financial aid to combat HIV/Aids to $30bn (£15bn) over the next five years.
"We will turn the tide against HIV/Aids once and for all," he said, adding that he would visit Africa during 2008.
In China, the Miss World pageant is coinciding with World Aids Day
Almost three-quarters of Aids-related deaths during 2006 were in sub-Saharan Africa. Two-thirds of those living with HIV are found there.
But the number of people living with the virus has increased everywhere, with the most striking increases in East Asia and Central Asia/Eastern Europe.
The BBC's David Loyn, in Afghanistan, says that nearly 30 years after HIV/Aids first emerged onto the world stage, it is now moving into the country with unpredictable consequences.
Only 266 cases of HIV/Aids have been recorded in Afghanistan but returning refugees, truck drivers, and Afghans now flying abroad to work are bringing in the disease.
There are fears the official figures are just the tip of the iceberg, our correspondent says.
Vatican view
In India, the Red Ribbon Express, a train with a giant Aids ribbon running the length of its side, has set off on a journey of almost 27,000km (16,000 miles) to spread advice about tackling the disease to almost 60,000 villages across the country.
An estimated two and a half million people in India are affected by the Aids virus - only Nigeria and South Africa have higher numbers.
In India, the Red Ribbon Express is spreading anti-Aids advice
And Chinese President Hu Jintao has appeared on the front page of major state-controlled newspapers shaking the hand of a woman with HIV.
The head of the Roman Catholic Church, Pope Benedict XVI, has said this week that he is spiritually close to victims of Aids and their families, but the Vatican still opposes the use of condoms as a means of fighting the epidemic.
At his weekly general audience the pope called for stepped-up efforts to stop the spread of the HIV virus that causes Aids and deplored the disdain with which Aids sufferers are often treated.
Yet the Vatican refuses to end its opposition to the use of condoms.
Roman Catholics in many parts of the world, however, believe condom use helps save lives, according to an opinion poll published by a liberal Catholic group in the United States, Catholics for Choice.
According to the survey, a majority of Catholics living in Ghana, Ireland, Mexico, the Philippines and the US all believe that Catholic hospitals and government-funded clinics should be required to include condoms as part of Aids prevention.
White House on December 1, 2007. 
The 20th annual World AIDS Day was December 1, 2007. The theme selected by the World AIDS Campaign is "Stop AIDS: Keep the Promise" as it will be through 2010. The day was marked by thousands of events around the world.

"It is now time for bold leadership at all levels in order to turn the tide of HIV," said Felicita Hikuam, Global Programmes Manager, World AIDS Campaign. An estimated 33.2 million people around the world—one in every 200—are living with HIV, and approximately 6,800 people are infected with HIV and 5,700 people die of AIDS-related illnesses every day.

"The trend is encouraging but still for every person receiving treatment four others are newly infected," said Nelson Mandela, speaking at a concert in Johannesburg, South Africa. "If we are to stop the Aids epidemic from expanding, we need to break the cycle of new HIV infections. All of us working together with government, communities and civil society can make the difference that is needed," he continued.

As many as 50,000 people attended the concert in Johannesburg, South Africa, which was telecast around the world. It was organized by Nelson Mandela's 46664 AIDS campaign and featured performances by artists such as Peter Gabriel, Ludacris, Razorlight, the Goo Goo Dolls and Annie Lennox.

At a fundraiser in the town of Midrand, in the province Gauteng, near Johannesburg on Friday, singer Annie Lennox had strong words for the South African government's AIDS policies.

"AIDS, as Madiba Mandela has said, is a human rights issue and should be treated as such in order to avoid this genocide that is affecting millions and millions of people around the world," said Lennox in a speech. Lennox has previously been critical of the South African government's position on suggesting some AIDS medications were toxic. "It is unacceptable that treatment has not been made available to those who need it most," said Lennox.

The rock band Queen, which lost its lead singer Freddie Mercury to AIDS, released a new song entitled, ''Say It's Not True'', to coincide with World Aids Day. It has been made available as a free download from the band's website. "By making the song available for free, we hope to help Nelson Mandela with his campaign to get across the message that no-one is safe from infection," said Queen drummer Roger Taylor. "We have to be aware, we have to protect ourselves and those we love."

In China, people distributed AIDS prevention brochures in the streets and promoted safe sex in cities like Beijing and Shanghai. In Changsha, official warning signs were put on hotel bedstands. The government announced on Friday an allocation of CNY860 million for AIDS prevention and control. According to official reports, there are estimated to be 700,000 people living with HIV/AIDS in China.

Also in China, the Miss World 2007 was in Sanya on World AIDS Day. The pageant presented a special tribute to the fight against AIDS, with a televised speech from former South African President Nelson Mandela, along with traditional dancers from South Africa who joined the contestants in a special song.

Friday, United States President George W. Bush urged the United States Congress to double the 2003 Emergency Plan for AIDS Relief to US$30 billion over the next five years. "Above all, we rededicate ourselves to a great purpose: We will turn the tide against HIV/AIDS—once and for all," he said.

"I'm pleased to announce that Laura and I will travel to sub-Sahara Africa early next year," Bush said. Sub-Saharan Africa suffered nearly three-quarters of AIDS-related deaths during 2006 and is home to two-thirds of those living with HIV/AIDS.