China's offshore surveillance force will be beefed up to ensure that the country's maritime interests are fully protected amid increasing disputes with its neighbors.

By 2020, a total of 15,000 personnel, compared with 9,000 now, will serve in the China Maritime Surveillance (CMS) force under the State Oceanic Administration, a senior official with the CMS, who declined to be identified, told China Daily.

The CMS air arm will be increased to 16 planes and the patrol fleet will have 350 vessels during the period of the 12th Five-Year Plan (2011-2015), the official said, adding that the fleet will have more than 520 vessels by 2020.

Currently, nine aircraft, more than 260 surveillance vessels and 280 law enforcement vehicles are in operation.

The CMS launched the construction of 36 patrol ships and 54 speedboats last year, the official said.

The expansion plan was unveiled as China's biggest civilian maritime patrol ship was sent into the South China Sea to protect national "rights and sovereignty".

Haixun 31, from the Chinese Maritime Safety Administration, under the Ministry of Transport, sailed from Zhuhai, Guangdong province, on Wednesday on its way to Singapore for a two-week visit, the Xinhua News Agency said.

The 3,000-ton, helicopter-equipped ship will monitor shipping, carry out surveying duties, inspect oil wells and "protect maritime security", Xinhua said.

It also said that the ship will inspect foreign vessels anchored or operating in Chinese waters.

There have been an increasing number of intrusions by foreign vessels and planes into Chinese waters and airspace in recent years.

In 2010, the CMS monitored intrusions by 1,303 foreign ships and 214 foreign planes, compared with a combined 110 cases in 2007, the official said.

The CMS was founded in 1998 and its duties include patrolling territorial waters, monitoring exclusive economic zones and protecting the maritime environment.

It has bases in Dalian, Tanggu, Qingdao, Shanghai, Ningbo, Xiamen, Guangzhou and Beihai and an aviation base is under construction in Zhoushan, Zhejiang province.

China is facing new challenges in protecting its maritime rights, Gao Zhiguo, head of the China Institute for Marine Affairs at the State Oceanic Administration, said.

The China Ocean Development Report 2011, released by the institute in May, also said disputes at sea between China and other countries have been on the rise.

Vietnam, the Philippines, Malaysia and Brunei have competing claims over some Chinese islands in the South China Sea, according to the report.

Vietnam's navy conducted live-firing exercises on Monday after accusing Chinese boats of disrupting oil and gas exploration in its waters.

Despite the rising tension, the Foreign Ministry on Thursday reiterated that Beijing will not use force to solve the dispute.

China is "committed to maintaining peace and stability in the South China Sea", spokesman Hong Lei said at a regular news conference.

Luo Yongkun, a researcher with the China Institutes of Contemporary International Relations, told China Daily that better coordination is needed to solve maritime disputes between China and its neighbors.

Another senior official from the State Oceanic Administration said last month that the State Council, the Cabinet, is reviewing a regulation on offshore patrolling and law enforcement in China's exclusive economic zones and continental shelf.