A China Marine Surveillance (CMS) detachment on Sunday started a joint ship-helicopter patrol of the Xisha Islands in the South China Sea.

Three CMS ships -- the Haijian 83, Haijian 262 and Haijian 263 -- departed from the port of Sansha City at 9 a.m. and will be joined by the Haijian B-7103 helicopter as they patrol the waters for nine days, said Zhang Weijian, the on-site director of the mission.

Zhang said the detachment will start by patrolling 10 islands and reefs on Sunday, while law enforcement personnel on the ships will land on the islands of Zhaoshu and Beidao.

It is the first time for the Chinese maritime helicopter and ships to carry out a joint patrol around the Xisha Islands since Sansha City, which administers the three islands groups of Xisha, Zhongsha and Nansha, was officially set up in July last year.

Yang Zhong, deputy head of the detachment, said the team will carry out regular patrol and observation missions, including maritime space management and marine ecology and island protection.

The CMS ships are under the administration of the State Oceanic Administration. They have carried out regular patrols and law enforcement activities in waters under China's jurisdiction since 2006.