Updated

The Philippines and Vietnam have condemned China's new law that requires foreign fishermen to seek Beijing's approval to operate in much of the South China Sea, where overlapping territorial claims have increased tensions.

The Philippine Department of Foreign Affairs said in a statement Friday that the new regulation "escalates tensions, unnecessarily complicates the situation in the South China Sea, and threatens the peace and stability of the region."

Vietnam's Foreign Ministry spokesman Luong Thanh Nghi said a statement late Thursday that Hanoi has "undisputable" sovereignty over the Spratly and Paracel islands, and that "all foreign activities in these areas without Vietnamese acceptance are illegal and invalid."

The Philippines said it asked China for clarification. The statement by Manila said that the regulation, which took effect this month, reinforces China's expansive territorial claims and violates international law, particularly the U.N. Convention on the Law of the Sea. It also said that the rule was contrary to a 2002 declaration that China signed with the 10-member Association of the Southeast Asian Nations, including the Philippines and Vietnam, to refrain from changing status quo.

The Philippines and Vietnam are among the most vocal critics of China's claims over the virtually entire South China Sea, which infringe into their 200-mile (322-kilometer) exclusive economic zones. China and other claimants have each beefed up its navy and stepped up patrols around island groups also claimed by others, increasing the risk of confrontation.

The U.S. has also criticized China's move, calling it "provocative and potentially dangerous."