Washington, Jul 22 (IANS): The Biden administration officials are concerned that China could seek to declare a no-fly zone over Taiwan ahead of a possible visit by House Speaker Nancy Pelosi as an effort to upend the trip, potentially raising tensions even further in the region, CNN reported.

China could also respond by flying fighter jets further into Taiwan's self-declared air defence zone, which could trigger a response from Taiwan and the US, the official added. They did not detail what a possible response would entail, CNN reported.

China has sent warplanes into Taiwan's self-declared air defence zone identification zone many times in recent months, an act which does not violate any international law but which usually results in Taiwan taking precautionary defensive measures, including sometimes scrambling its fighter jets.

Chinese planes have not entered the island's territorial airspace -- the area extending 12 nautical miles from its coastline.

The State Department has called on China to cease its intimidation of Taiwan.

Pelosi has been planning a trip to Taiwan in the coming weeks, according to three sources familiar with the planning process, CNN reported.

While other members of Congress and former US officials have visited Taiwan this year, Pelosi would be the highest-ranking US lawmaker to visit Taiwan in 25 years. Then Speaker Newt Gingrich travelled to Taiwan in 1997.