Beijing lashed out Tuesday at plans by the United States and Southeast Asian countries to issue a joint statement calling for the peaceful settlement of territorial disputes in the South China Sea, saying that would only complicate matters and sharpen differences.

China claims sovereignty over the entire sea and all the island groups within it and regards any U.S. involvement in the disputes as unwelcome interference.

Foreign Ministry spokesman Jiang Yu said the disputes were a matter only for China and the countries directly involved. Countries without claims in the region should stay out, she said.

“We are concerned about any kind of statement that might be issued by the U.S. and ASEAN over the South China Sea,” Jiang said, referring to the 10-member Association of Southeast Asian Nations.

“Words or acts that play up tensions in the region and concoct conflicts and provocations in relations between countries in the region are against the common wish of the countries in the region to seek peace and development,” Jiang said.

Beijing issued similar complaints in July after U.S. Secretary of State Hillary Clinton told a regional security forum in Vietnam that the peaceful resolution of South China Sea disputes was an American national interest.

China was apparently caught off guard by the statement, which U.S. diplomats said was prompted by comments in March from a senior Chinese foreign policy adviser that Beijing now considered the South China Sea a “core interest” — a designation it reserves for highly sensitive sovereignty matters over which it would be willing to go to war.

China is also opposed to negotiations on the matter with ASEAN as a whole, preferring to bring its overwhelming strength and influence to bear in bilateral talks with the other individual claimants.

While taking no position on the conflicting sovereignty claims, the U.S. insists on unfettered access to one of the world’s busiest commercial sea lanes.

President Barack Obama will meet ASEAN leaders on Friday to discuss ways to bolster their alliance and discuss economic cooperation and security issues, including the South China Sea disputes.

They will issue a joint statement where Washington has proposed text to reaffirm the importance of freedom of navigation, regional stability, respect for international law and unimpeded commerce in the South China Sea, according to a draft of the statement seen Sunday by The Associated Press.

ASEAN members Vietnam, Malaysia, Brunei and the Philippines also claim South China Sea island groups, which lie amid rich fishing areas and possibly huge oil and natural gas deposits. The contested islands straddle busy sea lanes that are a crucial conduit for oil and other resources fueling China’s fast-expanding economy.

China says it doesn’t wish to restrict access to the region by other country’s ships and planes, but has repeatedly interfered with U.S. Naval surveillance missions in the area, saying those were forbidden under international law.

Associated Press