TAIPEI (AFP) - Taiwan's President has called on Taiwanese Americans to return home and vote in local elections this month, urging them to help safeguard the country's democratic values in the face of Chinese pressure.

In an address to the Taiwanese Association of America in Washington DC, Tsai Ing-wen said the island could always count on the expat group that has chapters across the US "to stand up and help in times of need".

"I want to make a plea to everyone, come back to Taiwan to vote, or call your relatives and friends in Taiwan to support us," she said.

"The whole world is watching whether the Taiwanese people are going to choose a pro-China party or a party that is committed to democracy and sovereignty," she added in a recorded message on Saturday that marked the association's 50th anniversary.

Tsai also said the relationship between Taiwan and the US has improved in recent years.

Earlier this year, US congress passed the Taiwan Travel Act and the 2019 National Defence Authorisation Act which promote high level visits and military exchanges between the two sides.

Tsai's Democratic Progressive Party (DPP) is struggling to retain control of several key cities in Taiwan, according to opinion polls ahead of major local elections on November 24.

The opposition Kuomintang Party (KMT), seen as China-friendly, is making headway in four of Taiwan's biggest cities.

The island-wide vote is seen as a crucial barometer for Tsai as she battles a backlash on domestic reforms and concerns over relations with China, which have become increasingly tense since she took office in 2016.

Tsai has repeatedly accused China of launching an online "fake news" campaign to influence voters.

"We cannot let the international community think that Taiwanese people will yield under China's suppression," she told DPP supporters at a weekend rally in Yilan.

Related Story Taiwan braces for Chinese cyber attacks ahead of elections

According to Taiwan's National Security Bureau, Taiwan is hit with 20 million cyber attacks every month, mostly from China.

Taiwan's Investigation Bureau is also probing Chinese influence on elections through campaign funding of candidates.

The investigation bureau's chief Leu Weng-jong told legislators last month that it was investigating 33 cases of alleged illegal Chinese campaign funding.

Taiwan set up a police task force last month to counter "fake news" from China, and the military has also announced it will set up a department to counter disinformation and cyber attacks.

In June, Taiwan authorities barred a television reporter from China from working in Taiwan, accusing him of spreading "fake news" at a time of heightened cross-strait tensions.

It is the first time a mainland Chinese reporter has been banned from the island for "creating cross-strait conflict," according to Taiwan's Mainland Affairs Council, which deals with its China relations.