BEIJING — The Central Military Commission, China’s most powerful military body, has approved the deployment of a garrison of soldiers from the People’s Liberation Army to guard disputed islands claimed by China and Vietnam in the South China Sea, the state-run Xinhua news agency said Sunday.

On Monday, there was a first meeting of the 45 legislators elected over the weekend to govern the 1,100 people who live on the island groups of the Spratlys, the Paracels and the Macclesfield Bank, Chinese authorities told state media. The meeting was the latest escalation of the territorial dispute between China and its neighbors over the island groups, known in Chinese as the Xisha, Zhongsha and Nansha Islands.

The new legislators will not only govern the island groups, many of which consist of rocks and atolls, but also about 772,000 square miles of the South China Sea over which China claims jurisdiction, state media said.

The troop deployment and elections appeared intended to reinforce China’s claims over the South China Sea and its potential energy resources. The moves came a week after a meeting of foreign ministers of the Association of South East Asian Nations in Phnom Penh, Cambodia, at which China, according to diplomats at the meeting, used its influence to stop even a rudimentary communiqué on the South China Sea among the 10 nations.