Chinese state media warned on Friday that a report by a prominent U.S. think tank on the military uses of Chinese scientific research across the Indian Ocean gave "ammunition" to countries bent on concocting threats from China.

The aircraft carrier USS Carl Vinson transits the Indian Ocean.

The report this week by the Washington-based Center for Strategic and International Studies (CSIS) "comes at a time when some countries need to manufacture a 'China threat' narrative in the Indian Ocean region and provides them with ammunition", the state-controlled tabloid Global Times said in an editorial.

"The timing of this report is delicate," given that the Maldives and China are upgrading ties after the election of President Mohamed Muizzu, while Sri Lanka recently suspended foreign research vessels, including from China, from visiting its ports.

The CSIS study traced data over four years of deployments by nominally Chinese civilian oceanographic and energy research ships, concluding that the work would in part serve the Chinese navy's needs to project power into the region.

Detailed knowledge of ocean depths, currents and temperature was vital to China's growing submarine operations, the study said.

"While scientific and commercial benefits may accrue from Chinese oceanographic research, these activities may also prove crucial for the (People's Liberation Army) in expanding its operational reach and capabilities in the Indian Ocean," it said.

"This expansion poses a significant challenge to key regional players like India, as well as to the United States and its allies."

Chinese foreign ministry spokesperson Mao Ning said China's marine scientific research fully complied with the U.N. Convention on the Law of the Sea.

"We hope that the relevant parties will take an objective view of China's marine scientific research activities and refrain from speculating through coloured glasses," Mao said.

The Chinese defence ministry did not immediately respond to faxed requests for comment.

Reuters last month outlined extensive Chinese military vulnerabilities across the Indian Ocean, where the its navy lacks a hard base network and air cover despite its reliance on oil shipments through the region.

The Global Times defended ongoing research missions, saying China and regional partners were exploring the natural ecology of the region "without any hidden agenda".

"The Indian Ocean is one of the least understood oceans by the scientific community, and a fundamental reason is the lack of sufficient on-site observations."