Sarah Left explains the causes and history of the bloody west African conflict that has left 200,000 Liberians dead in 14 years of fighting

Rebel forces backed by neighbouring countries are fighting to oust Liberia's warlord-turned-president, Charles Taylor.

Two main rebel groups have succeeded in pinning Mr Taylor's government into a final stronghold: the capital, Monrovia. At least 1,000 civilians have died in the past two months of intense fighting.

One rebel leader said his group would surrender their positions to peacekeepers when they have secured the city. The US has said it will not send in troops until Mr Taylor leaves. Mr Taylor, who has accepted an offer of asylum from Nigeria, has agreed to step down on August 11. However his promise was conditional, and he may or may not cede power by that date.

Meanwhile, the rebels continue to press into Monrovia, and the government troops keep fighting to hold them back. Residents and refugees in Monrovia are running out of food and clean water.

Why are the rebels trying to oust Mr Taylor?



Mr Taylor's financial support for rebel forces in Guinea, Ivory Coast, and Sierra Leone created enormous hardship in those countries. The UN banned sales of diamonds from Liberia in 1990, in an attempt to cut off Mr Taylor's source of funds and thus limit the amount he could funnel to rebel insurrections in neighbouring countries.

His contributions to rebels in Sierra Leone fuelled a bitter civil war in that country. His main ally, the Revolutionary United Front, has been accused of widespread torture and sexual assault. In June, a UN-backed court indicted Mr Taylor for crimes against humanity during the civil war in Sierra Leone.

Guinea and Ivory Coast have similar complaints. All three countries have repaid the favour by supporting rebels inside Liberia.

Who are the rebels?



Two rebel groups from different tribal backgrounds now control most of Liberia.

The Liberians United for Reconciliation and Democracy (Lurd) grew out of Mr Taylor's old foes from the 1990-1996 civil war. Sheltered by Guinea and Sierra Leone, Lurd launched its attack on Monrovia after taking the northern third of the country.

The Movement for Democracy in Liberia (Model), supported by Ivory Coast, emerged earlier this year and took the southern third of the country. This group is also now closing on Monrovia.

Is the tension all down to external factors?



No, there are underlying tensions in Liberia. The African-Americans who founded the country in the early 1800s did not reconcile with the indigenous Africans. The relatively small group of Americo-Liberians held power until 1980, when Samuel Doe assassinated the serving American-descended president.

Mr Taylor's father was Americo-Liberian and his mother an indigenous African. Model and Lurd have differing ethnic memberships, which could contribute to tension.

How did it come to this?



The country's civil war began in 1989, when Charles Taylor returned to Liberia from neighbouring Ivory Coast. He brought with him a force of 100 rebels - the National Patriotic Front of Liberia - seeking to oust the repressive regime of the then-president, Samuel Doe.

A rival warlord, Prince Yormie Johnson, seized, tortured and executed Doe in front of video cameras in September 1990. But the demise of Doe's corrupt, abusive regime failed to bring about stable democratic government.

Johnson and Mr Taylor turned on each other, plunging Liberia into seven years of civil war.

The west African peacekeeping force, Ecomog, eventually stepped in. Mr Johnson accepted asylum in Nigeria, and Mr Taylor finally found himself in a position to hold elections in July 1997, despite his failure to secure the entire country.

He took 75% of the vote from a war-weary electorate desperate for an end to the violence. One of Mr Taylor's campaign slogans ran: "He killed my Ma, he killed my Pa, but I will vote for him."

Just as Doe's assassination brought only more war, Mr Taylor's election failed to end the violence.

How many people have been killed in the conflict?



Over the last 14 years of on-again, off-again fighting, around 200,000 Liberians have died. Another 1.5 million have been forced to flee their homes.

Are any peacekeepers on the way?



A West African peacekeeping force - expected eventually to total between 3,000 and 5,000 troops - is the vanguard. Nigeria deployed an advance force of about 200 troops on August 4 to secure Monrovia's airport and set up a base of operations.

The UN security council approved a multinational force on August 1, with plans for UN peacekeepers to take over in few months.

But even if Mr Taylor leaves for Nigeria, as did Prince Johnson before him, peace will not necessarily follow. There is no guarantee that the two main rebel factions in Liberia would not continue to fight each other.

Why has the US not sent troops to the country?



Liberia was founded by former US slaves in 1847, leading to calls that America has a special responsibility to protect the lives of Liberian civilians now.

So far the US has sent only a handful of troops to safeguard its embassy in Monrovia. George Bush has ordered three ships to take up positions off Liberia's coast, but has made no specific commitment to putting troops on the ground.

In 1990, the administration of George Bush sr also deployed marines off the coast of Liberia. They assisted with the evacuation of American citizens, but never came ashore for peacekeeping duties.