Taiwan on Friday said its top representative to Hong Kong has returned home due to "unnecessary political obstacles", with local media reporting he refused to sign a pro-Beijing statement.

China has been angered by Taiwan's support for the city's pro-democracy protests and the government's decision to open an office to help Hong Kongers who want to relocate to the island.

Beijing's new national security law, imposed on Hong Kong late last month, has further strained ties, ordering Taiwanese political organisation to declare staff and assets.

China imposed a new national security law on Hong Kong late last month, straining ties with Taiwan
China imposed a new national security law on Hong Kong late last month, straining ties with Taiwan AFP / Anthony WALLACE

Kao Ming-tsun, acting director of Taipei Economic and Cultural Office, "was forced to return to Taiwan because the Hong Kong side violated the consensus and set up unnecessary political obstacles", said Chiu Chui-cheng, spokesman of the Mainland Affairs Council (MAC), Taiwan's top China policy body.

Chiu declined to elaborate on what the obstacles were.

Taiwan's Up Media news said Kao refused to sign a statement supporting Beijing's view that Taiwan is part of "one China" when he was renewing his work visa.

A source in Taipei with knowledge of Kao's decision told AFP he did refuse to sign the statement presented by the Hong Kong authorities.

Taipei officials routinely avoid travelling to Hong Kong due to recent frictions
Taipei officials routinely avoid travelling to Hong Kong due to recent frictions AFP / Anthony WALLACE

Taiwan's President Tsai Ing-wen rejects the idea of "one China" and views the democratic, self-ruled island as de facto independent nation.

That stance infuriates Beijing which regards Taiwan as its territory and has vowed to one day seize it, by force if necessary.

It has ramped up economic, diplomatic and military pressure since Tsai's 2016 election.

Relations between Taiwan and semi-autonomous Hong Kong have also rapidly deteriorated.

The office handling unofficial ties has already been devoid of a chief since mid-2018 with Hong Kong yet to issue a visa. Taipei officials routinely avoid travelling there.

Under the new national security law, Beijing says it can prosecute national security crimes committed overseas, including by foreigners.

That has sparked concerns Taiwanese nationals and other foreigners who are critical of Beijing could be arrested travelling to or transiting through Hong Kong.

On Thursday, Taiwan warned China could use the new security law for "hostage diplomacy" and urged democratic countries to unite against Beijing's "autocratic" expansion.

China