China and Russia are working on a joint invasion of Taiwan, US intelligence officials have claimed.

‘We see China and Russia, for the first time, exercising together in relation to Taiwan and recognising that this is a place where China definitely wants Russia to be working with them, and we see no reason why they wouldn’t,’ Avril Haines, Director of US National Intelligence, told the US Congress on Thursday.

Her warning on the potential cooperation between the countries on Taiwan, which China has long claimed as its own territory to be annexed force if necessary, was echoed Lieutenant General Jeffrey Kruse.

He said that the US Defence Department has ‘become even more concerned about our joint force requirements in an environment where [Russia and China] would certainly be cooperative, and we need to take that into account,’ Bloomberg reports.

A potential joint invasion of Taiwan was raised in the meeting of the Senate Armed Services Committee Republican Senator Mike Rounds, who asked the head of the Defence Intelligence Agency about the Pentagon’s plans should an invasion happen.

Haines said that there seems to be an ‘increasing cooperation in the “no-limits” partnership’ between Russia and China.

This comes as Chinese leader Xi Jinping is expected to make his first trip to Europe next week as part of China’s efforts to rebuild its foreign relations.