Southeast Asian foreign ministers urged restraint Thursday as China readied massive military drills off Taiwan, warning the situation risked spiraling into open conflicts.

A furious Beijing is planning its biggest-ever exercises around Taiwan in response to US House Speaker Nancy Pelosis visit to the self-ruled island.

Ministers from the 10-member Association of Southeast Asian Nations (ASEAN) meeting in Phnom Penh warned against provocative action.

The situation could lead to miscalculation, serious confrontation, open conflicts and unpredictable consequences among major powers, the ministers said in a joint statement published Thursday.

Beijing, which considers Taiwan a part of its territory to one day be reclaimed, by force if necessary, was enraged by the trip by Pelosi -- the highest-profile elected US official to visit the island in 25 years.

It vowed punishment and announced military drills, including live-fire exercises, expected to begin at 0400 GMT in several areas encircling Taiwan.

EU foreign policy chief Josep Borrell, in Phnom Penh for talks with ASEAN, condemned the Chinese response.

There is no justification to use a visit as pretext for aggressive military activity in the Taiwan Strait. It is normal and routine for legislators from our countries to travel internationally, he tweeted.

Kung Phoak, Cambodias deputy foreign minister and ASEAN spokesman, urged both sides to stabilize the situation.

We hope de-escalation happens… and normalcy returns to the Taiwan Strait, he told reporters.

ASEAN is split between countries with close ties to China, such as Myanmar, Cambodia and Laos, and others that are warier of Beijing and its growing international assertiveness.

But no ASEAN country formally recognizes Taiwan and none have shown an appetite for backing Taipei against the communist giant.