WASHINGTON (REUTERS) - The White House on Friday (April 9) said it was keeping a close watch on increased Chinese military activities in the Taiwan Strait, and called Beijing's recent actions potentially destabilising.

"We have... clearly - publicly, privately - expressed our concerns, our growing concerns, about China's aggression towards Taiwan," White House press secretary Jen Psaki told reporters.

"We've seen a concerning increase in PRC military activity in the Taiwan Strait, which we believe is potentially destabilising," she said, when asked if Washington was concerned about a possible Chinese invasion.

Chinese-claimed Taiwan has complained over the last few months of repeated missions by China's air force near the island, concentrated in the southwestern part its air defence zone near the Taiwan-controlled Pratas Islands.

Eleven Chinese air force aircraft entered Taiwan's air defence identification zone on Friday, including eight fighter jets, the island's defence ministry said.

Beijing on Thursday blamed the United States for tensions over Taiwan after a US warship sailed close to the island, asking rhetorically whether China would sail in the Gulf of Mexico as a "show of strength."

On Monday, China said a Chinese aircraft carrier group was exercising close to the island, and on Wednesday a US warship sailed through the sensitive Taiwan Strait that separates the island from its giant neighbour.

Taiwan is China's most sensitive territorial issue and a major bone of contention between Beijing and Washington, which is required under US law to provide the island with the means to defend itself.

China believes the United States is colluding with Taiwan to challenge Beijing and giving support to those who want the island to declare formal independence.