Malaysian Prime Minister Anwar Ibrahim said on Tuesday China was worried about activity by the state energy firm Petronas in a part of the South China Sea that Malaysia says is its territory.

Anwar said he was open to negotiations with China, drawing criticism from the opposition, which said Anwar was risking Malaysia’s sovereignty.

The foreign ministry said in a Saturday statement Anwar’s comment meant Malaysia would like all issues related to the South China Sea to be resolved in a peaceful manner and without compromising Malaysia’s position.

“The government of Malaysia is unequivocally and firmly committed to protecting Malaysia’s sovereignty, sovereign rights and interests in its maritime areas in the South China Sea,” the ministry said.

China claims sovereignty over almost the entire South China Sea, through which about $3 trillion worth of ship-borne trade passes annually. Malaysia, Brunei, the Philippines, Taiwan and Vietnam have some overlapping claims.

Petronas operates oil and gas fields within Malaysia’s exclusive economic zone (EEZ) and has in recent years had several encounters with Chinese vessels.

China stakes its claim with a reference to a “nine-dash line” on its maps, which loops as far as 1,500 km south of its mainland, cutting into the EEZs of Vietnam, the Philippines, Malaysia, Brunei and Indonesia.

The Permanent Court of Arbitration, however, ruled in 2016 that the nine-dash line has no legal basis.

Anwar said this week Petronas would continue its activities in the South China Sea.