A war of words erupted on Friday between China and Taiwan, hours after Taiwan election authorities declared President Chen Shui-bian re-elected despite an office invasion by angry supporters of his narrowly defeated challenger.
In its strongest statement yet on the political crisis convulsing an island Beijing regards as a renegade province, China said it would not sit idly by if protests over last weekend's disputed presidential election spun out of control.
The bitter rivalry between Nationalist Party challenger Lien Chan and incumbent Chen, who won by a margin of just 0.2 percent, threatens a prolonged crisis that could paralyse policymaking in one of Asia's most vibrant economies.
Chen governs but lacks a majority in parliament. Ignoring protesters who stormed their offices, smashing windows, throwing stones and eggs and scuffling with riot police, the election commission agreed that Chen was indeed the winner.
"Truth unclear, suspend declaration", shouted several hundred demonstrators. "Down with the commission."
Their anger was echoed by Beijing, which is anxious to prevent pro-independence activists who support Chen's aggressive policy of greater sovereignty for the island from using the turmoil to promote their cause.
"We will not sit by watching should the post-election situation in Taiwan get out of control, leading to social turmoil, endangering the lives and property of our flesh-and-blood brothers and affecting stability across the Taiwan strait," Beijing's policy-making Taiwan Affairs Office said in a statement.
It took note that the result had been declared without regard to opposition complaints and the opposition was persisting with its refusal to recognise the outcome.
"We are closely following the developments in Taiwan."
The first victim of the turmoil has been Taiwan's stock market, which had been Asia's best-performing outside China this year but has lost nearly 10 percent since trading reopened on Monday after the election.
Beijing was unlikely to follow up such words with action. It was using the rhetoric, which it had restrained for months to prevent stoking anti-China sentiment, to warn off independence supporters from disrupting a planned Saturday demonstration by up to half a million Lien supporters, analysts said.
Taiwan swiftly hit back, telling Beijing to mind its own business.
"Communist China has no reason to criticise our internal affairs. It is crudely interfering in our internal affairs," the policy-making Mainland Affairs Council said, and expressed great dissatisfaction.
The Republic of China, the island's official name since it split from the mainland after the Nationalists fled there after losing a civil war to the communists in 1949, was capable of dealing with internal dissent, it said. Thousands of protesters massed outside the presidential palace for a sixth day, insisting that the result was unfair and spinning conspiracy theories about the assassination attempt.
Police investigating the shooting said they were seeking a balding man caught on a security camera as he ran from the scene in the southern city of Tainan.