China has urged the United States to refrain from having any official contact with Taiwan, thus harming China-US ties, after the US House of Representatives passed a bill encouraging visits between US and Taiwan officials.

The Taiwan Travel Act, which was passed by the House on Tuesday, has yet to be passed by the US Senate and signed by President Donald Trump to become law.

Foreign Ministry spokesman Lu Kang expressed on Thursday China's firm opposition to the bill. "The bill violates gravely the one-China policy and the principles established in the three China-US joint communiques, and is an interference into China's internal affairs," Lu said at a daily news conference.

Lu urged the US "not to conduct any official exchanges or contact with Taiwan, and not to send any wrong signals to 'Taiwan independence' forces".

The US should handle the Taiwan question with caution and take concrete actions to maintain the general situation of China-US ties and bilateral cooperation in international affairs, the spokesman said.

Beijing had voiced its opposition in October after the bill was advanced by the US House Foreign Affairs Committee.

The United States severed diplomatic ties with Taiwan in 1979 and established such ties with the People's Republic of China. The joint communique on the establishment of China-US diplomatic ties shows the US should maintain only unofficial relations with Taiwan.

Ruan Zongze, vice-president of the China Institute of International Studies, said the move by the US House of Representatives is "vile in nature", as it is a challenge to the three China-US joint communiques as well as encouragement to the "Taiwan independence" forces.

China will not compromise on the Taiwan question, which concerns China's core interests, and will certainly take countermeasures if the bill becomes law, Ruan said.