By Louisa Lim
BBC News, Beijing
Both Taiwan and China have increased their military power
Saturday's rally is to protest against a new Chinese law which would authorise the use of force against Taiwan if the island pushed for formal statehood.
China sees Taiwan as a breakaway province, and this bill gives it a legal basis to attack the island if it declares independence.
The march organisers are hoping to get a million people onto the streets.
Taiwan's President Chen Shui-bian has said he will join the march, which he has tried to paint as a peaceful rally aimed at protecting the island's democracy.
TAIWAN-CHINA RELATIONS Ruled by separate governments since end of Chinese civil war in 1949 China considers the island part of its territory China has offered a "one country, two systems" solution, like Hong Kong Most people in Taiwan support status quo
Warning to Taiwan Taiwan Flashpoint
But China's state-run media is warning that the protests could worsen already tense relations between the two sides.
It quotes academics, who are often used as government mouthpieces, expressing fears that secessionist forces might use the march to fan anti-mainland sentiment.
China has tried to play down its new law, saying it is not a war bill.
But the law has drawn angry protests in Taiwan, where the government described it as a blank cheque for an attack on the island.
The new bill has also been criticised by the US, and has increased pressure on the European Union not to lift its arms embargo on China given the rising tensions across the Taiwan Strait.
Over 500 groups, including the Democratic Progressive Party, are planning a massive march and rally for Saturday in Taipei City. March promoters are vowing to bring one million people onto the streets to protest the People's Republic of China's "anti-secession" law aimed at thwarting Taiwan independence.

The march, titled "326 March for Democracy and Peace", will begin in ten different locations, converging on the square near the Presidential Office in downtown Taipei City.

"Democracy and peace are the ultimate goal of the march," said Joseph Wu, the Mainland Affairs Council Chairman. Wu announced on Friday that he would take part in the rally, but did not disclose in which part of the parade he would appear.

Taiwan's President Chen Shui-bian announced on Thursday that he will also attend the event with his family.

"I cannot and will not be absent on March 26, and I will take my entire family to participate in this sacred moment in history to walk and stand up together with the Taiwanese people," Chen said. Chen further declared that he has, "heard the outrage and anger of the Taiwan people."

A Chinese scholar warned that the situation could become "further aggravated" by Saturday's planned event.

"The secessionist forces plot to stir up public sentiments to embolden themselves. Such moves are doomed to meet failure," said Huang Jiashu, a professor at the People's University of China. He stated that secessionist forces had "malevolently distorted" the anti-secession law.

The ''Taiwan Domestic News Hour'' on ''ETTV'' is running a ''326'' graphic to note the march and rally during its news reports about the upcoming event, and also has an animated graphic with marchers carrying signs in the lower-left hand corner of the screen.