MANILA — Philippine President Rodrigo Duterte has ordered an end to all foreign scientific research missions in a vast expanse of waters off the country’s northeast and called on the military to “chase out” unauthorized vessels, an official said on Tuesday.

Duterte issued the order in a Cabinet meeting late Monday after doubts were raised over the country’s sovereign rights in the offshore region called Benham Rise, which the government has renamed Philippine Rise, said Agriculture Secretary Emmanuel Pinol.

“Let me be very clear about this: The Philippine Rise is ours and any insinuation that it is open to everybody should end with this declaration,” Pinol quoted Duterte as telling Cabinet members.

Benham Rise is an off-shore frontier facing the Pacific Ocean that is approximately 24 million hectares (59 million acres) in size and is in the Philippines’ exclusive economic zone, an area where nations have internationally recognized exclusive rights to exploit fish and fuel resources, and continental shelf further out in the ocean.

Philippine security officials raised concerns about intrusions when a Chinese ship was monitored crisscrossing the waters early last year, drawing public attention to the territory, which some believe could have undersea gas and oil deposits aside from its rich fishing grounds.

Benham Rise lies on the other side of the Philippine archipelago from where Manila, Beijing and four other governments have been locked for decades in territorial disputes in the South China Sea.

Duterte’s spokesman, Harry Roque Jr., told a news conference on Tuesday that all foreign scientific groups, including from China, Japan, South Korea and the United States, have concluded their research work in the waters and the president wants Filipinos to carry out research from now on.

About 30 existing research permits would be deemed revoked and foreign scientific research groups may reapply but should get additional permission from Duterte’s national security adviser due to the security implications of their presence in the waters, Roque said.

While the Philippines could halt foreign scientific research, foreign ships could freely pass through the waters under an international maritime treaty but could not tap its resources or lay submarine cables, Roque said.

Critics have questioned why the Duterte administration allowed a group from China to undertake scientific research in the waters given Manila’s long-simmering territorial conflict with Beijing in the South China Sea. China has also defied and refuses to comply with an international arbitration ruling that heavily favored the Philippines in the disputed South China Sea.

Rep. Gary Alejano, a former marine officer, has said the government’s decision to give Chinese surveyors access to Benham Rise was “careless and absurd” and may have undermined the country’s national security. He expressed doubts the Chinese would adequately share the information they gathered as required by the Philippine government.

Tensions between China and the Philippines over South China Sea territories have eased considerably since Duterte took office in mid-2016 and began reaching out to China. He has placed the dispute on the backburner while seeking Chinese trade and economic aid, sparking concerns from nationalists and left-wing group alarmed by China’s continuing actions to reinforce its claims in the disputed waters. — AP