BEIJING — China said Tuesday it has complained to the U.S. over legislation expressing support for Taiwan's bid for observer status at the International Civil Aviation Organization.

China, which split with Taiwan amid civil war in 1949, opposes the island's efforts to join most international organizations.

Foreign Ministry spokeswoman Hua Chunying said in a statement that the U.S. bill has "seriously violated" the one-China policy under which Beijing says self-governing Taiwan is part of Chinese territory and sooner or later needs to come under its control.

China urges Washington to "stop interfering in China's internal affairs," Hua said.

The U.S. legislation backs allowing Taiwan to observe the assembly of the U.N. organization, which promotes safe air travel. The assembly meets every three years and its next meeting is in September.

The legislation says observer status will help ensure Taiwan's ability to conform to international safety standards.