The US should formally recognize Taiwan, former Secretary of State Mike Pompeo said during a speech in Taipei, Reuters reports.

"The United States government should immediately take necessary and long overdue steps to do the right and obvious thing: that is to offer the Republic of China, Taiwan, America's diplomatic recognition as a free and sovereign country," Pompeo said in a speech organised by a Taiwan think-tank.

Washington severed formal diplomatic relations with Taiwan in 1979 when it recognized the People's Republic of China.

"While the United States should continue to engage with the People's Republic of China as a sovereign government, America's diplomatic recognition of the 23 million freedom-loving Taiwanese people and its legal, democratically-elected government can no longer be ignored, avoided, or treated as secondary," Pompeo said.

China imposed sanctions on "lies and fraud" Pompeo and 27 other senior Trump-era officials when President Joe Biden took office in January 2021.

The Donald Trump administration has strongly supported Taiwan despite the absence of official diplomatic relations, endorsing arms sales and visits by senior US officials to Taipei.