BEIJING (Reuters) - China has “reasonably” expanded its islands in the disputed South China Sea and this year construction projects there including radar facilities covered about 290,000 square meters (72 acres), according to a new government report.

An aerial view of China occupied Subi Reef at Spratly Islands in disputed South China Sea April 21, 2017. REUTERS/Francis Malasig/Pool

The number was broadly similar to one provided by a U.S. think tank earlier this month.

China has conducted extensive land reclamation work on some of the islands and reefs it controls in the South China Sea, including building airports, alarming its neighbors and Washington.

Beijing says the work is help provide international services such as search-and-rescue but admits there is a military purpose too. China also says it can do whatever it wants on its territory.

The new report, posted on a website run by China’s National Marine Data and Information Service and the overseas edition of the ruling Communist Party’s People’s Daily, says China has enhanced its military presence there and “reasonably” expanded the area covered by the islands.

Apart from what it termed “large radar” - it was unclear if the report was referring to more than one - construction this year has included facilities for underground storage and administrative buildings.

There has been an increase in military patrols too, the report added, without giving specifics.

The report was released on Friday but appeared in the state-run newspaper the Global Times on Monday.

While attention in Asia has been distracted by the North Korean nuclear crisis in the past year, China has continued to install high-frequency radar and other facilities that can be used for military purposes on its man-made islands in the South China Sea, a U.S. think tank said this month.

That report, by the Asia Maritime Transparency Initiative of Washington’s Center for Strategic and International Studies, said Chinese activity has involved work on facilities covering 72 acres (29 hectares) of the Spratly and Paracel islands, territory contested with several Asian neighbors.

More than $5 trillion of world trade is shipped through the South China Sea every year. Besides China’s territorial claims in the area, Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.