China described its military exercises near Taiwan as "combat drills" on Wednesday, upping the ante as senior former U.S. officials arrived in Taipei on a trip to signal President Joe Biden's commitment to Taiwan and its democracy.

Taiwan has complained over the proximity of repeated Chinese military activity, including fighter jets and bombers entering its air defence zone and a Chinese aircraft carrier exercising off the island, which is claimed by Beijing.

Twenty-five Chinese air force aircraft, including fighters and nuclear-capable bombers, entered Taiwan's air defence identification zone (ADIZ) on Monday, the largest reported incursion by Taipei to date.