* Taiwan: Chinese fighters crossed Taiwan Strait median line

* Median line serves as unofficial buffer between the two

* China says it carried out combat exercises near Taiwan

* Senior U.S. senator in Taipei meeting President Tsai (Recasts, adds Taiwan Defence Ministry statement)

By Yimou Lee and Martin Quin Pollard

TAIPEI/BEIJING, July 8 (Reuters) - Chinese fighter jets crossed the median line of the sensitive Taiwan Strait on Friday in what the island's government slammed as a provocation, as a senior U.S. senator visited Taipei for a meeting with President Tsai Ing-wen that China condemned.

China claims democratically-ruled Taiwan as its own territory and has ramped up military and political pressure to try and force the island to accept Chinese rule.

Taiwan's Defence Ministry said the Chinese aircraft "intentionally crossed the median line of the strait in a provocative move, which has seriously damaged regional peace and stability".

It said Taiwan's air force "forcefully expelled" the Chinese aircraft and deployed ground-to-air missiles to "monitor" the situation.

The median line is an unofficial buffer between China and Taiwan and normally military aircraft stick to their respective sides, but on occasion China's air force crosses over it, as happened in 2020 when U.S. officials were visiting Taiwan.

Several Chinese fighter jets crossed the median line of the Taiwan Strait on Friday in the northern part of the waterway, a Taiwan source briefed on the matter told Reuters, adding the aircraft did not enter Taiwanese airspace.

The source said it was rare for Chinese aircraft to cross the unofficial buffer, especially from Taiwan's northwest.

The aircraft "flew straight across" the median line and then "circled around" carrying out tactical operations, the person said, adding that Taiwan scrambled fighter jets to intercept the Chinese planes.

"It was a clear message of provocation," the person said, citing Friday's visit to Taipei by U.S. Senator Rick Scott, a senior Republican who chairs the National Republican Senatorial Committee and sits on the Senate's Armed Services Committee.

Earlier on Friday, China's military said it had held joint combat readiness exercises, patrols and combat drills in the sea and airspace around Taiwan.

The exercises, announced by the Eastern Theatre Command of the People's Liberation Army, were organised in response to "collusion and provocations" by the United States and Taiwan, Chinese Defence Ministry spokesman Wu Qian said in a statement.