A win for the ruling party candidate William Lai would pose a danger to relations, China said.

It also criticised "brazen chattering" by the US after Washington warned Beijing not to stoke tensions ahead of Saturday's vote.

Who wins the poll could push the island further towards, or away from, Beijing.

Taiwan is a key flashpoint in the tussle between China and the US for supremacy in Asia.

China's Taiwan Affairs office said Mr Lai would further promote separatist activities if he were elected.

"[He] would continue to follow the evil path of provoking 'independence' and... take Taiwan ever further away from peace and prosperity, and ever closer to war and decline," it said in a statement.

Mr Lai, of the Democratic Progressive Party (DPP), has called for voters to "choose the right path" to maintain Taiwan's sovereignty. His main opponent, Hou Yu-ih of the Kuomintang (KMT), has called Mr Lai a danger to relations with China.

Democratic Progressive Party supporters at a Taipei rally on Thursday - most Taiwanese want to keep the status quo

Many Taiwanese consider themselves to be part of a separate nation - although most are in favour of maintaining the status quo where Taiwan neither declares independence from China nor unites with it.

The island sees itself as distinct from the mainland - but China's government says it is a breakaway province that will, eventually, be part of the country, and has not ruled out the use of force to achieve this.

Mr Lai had been narrowly in front in the presidential race before polling stopped on 2 January. Parliamentary elections are also being held.

China's message to voters came as it told the US to stop commenting on the election.

The foreign ministry in Beijing issued a sharp rebuke to Washington after the US said it would send an unofficial delegation to Taiwan after the vote.

The US government must "refrain from intervening in the elections... so as to avoid causing serious damage to US-China relations", a spokesperson said.

China "expresses... resolute opposition to the American side's brazen chattering about the elections in the Taiwan region".

Beijing has said Taiwan's voters face a choice between peace and war in the elections.

On Thursday's Taiwan's Foreign Minister Joseph Wu criticised China for its "repeated interference" in Saturday's vote.

"Frankly, Beijing should stop messing with other countries' elections & hold their own," Mr Wu posted on X, the social platform formerly known as Twitter.

By Simon Fraser