Britain’s House of Commons Foreign Affairs Committee is planning a visit to Taiwan later this year – likely in November or early December – despite rising tensions in the region, the Guardian has learned.

Sources say the trip – which was originally planned for the start of this year but was postponed due to a delegation member testing positive for Covid – was intended to show Britain’s support for the democratically run island, which China considers its own.

It comes as London’s relationship with Beijing continues to deteriorate. Last week, Conservative leadership candidates Liz Truss and Rishi Sunak voiced their tough stances on China. And China’s ambassador to the UK accused some UK politicians of “peddling the fallacy of the so-called Chinese threat” in a video remark.

Tensions have risen in the Taiwan Strait in recent weeks after reports of a possible trip to Taipei by US House of Representatives Speaker Nancy Pelosi. Beijing has repeatedly warned against such a move and threatened to take “decisive action” if the trip continues. Pelosi is now on a trip to Asia, where she has scheduled stops in Singapore, Malaysia, Japan and South Korea.

On Saturday, China’s People’s Liberation Army (PLA) conducted “live-fire drills” near Pingtan Island off Fujian province, according to the official Xinhua news agency. China’s Maritime Safety Administration has warned ships to avoid the area. The drills also preceded the anniversary of the PLA’s founding on August 1.

In their fifth phone call last week, Chinese President Xi Jinping warned US President Joe Biden not to “play with fire” over Taiwan. On Monday, China’s spokesman said his military “would not sit idly by” if Pelosi continued his trip to Taiwan.

Tom Tugendhat, who chairs the foreign affairs select committee, is expected to lead the delegation to Taiwan later this year. But as he extended his support for Truss over the weekend, there was speculation he could secure a cabinet-level position in her administration if she won the race in September. But even if that happened, a source said, the journey would continue “whoever becomes the next president.”

It is unclear whether the British delegation would meet Taiwan President Tsai Ing-wen. Details of the trip are being worked out, including dates for the visit, sources suggested. In the past, the Taiwanese leader has personally hosted delegations from the European Parliament and members of the US and Czech senates.

The move is another sign that London is strengthening its ties with Taiwan, as it now sees China as a long-term threat to the UK. Officially, Britain continues to stick to its “one China policy”, which recognizes Beijing as China’s only legal government, but it maintains ties with Taiwan at an unofficial level.

Truss, the foreign minister, has in recent months urged Western countries to ensure that Taiwan can protect itself from China. In June, she remarked in an interview that the UK should supply arms to Taiwan – a comment that surprised some of her fellow MPs and colleagues, according to the Guardian.

Taipei’s representative office in London declined to comment on details of the potential visit when approached by the Guardian, but said Taiwan “welcomes all opportunities to strengthen its relationship with Britain, including through visits from the UK”.

The Foreign Affairs Committee said it “has long intended to visit Taiwan, as part of its investigation of the Indo-Pacific tilt.” But he declined to comment on details of the visit “for security reasons and in line with normal practice”.