BEIJING, April 29 (Xinhua) -- A Chinese marine surveillance team returned to south China's Guangzhou City on Monday after completing regular patrol operations in the South China Sea, according to the State Oceanic Administration.

The team, consisting of two China Marine Surveillance ships -- Haijian 84 and Haijian 74, patrolled the Xisha and Nansha islands and their nearby waters for 12 days. The team covered a distance of more than 4,500 nautical miles, the administration said.

During the patrols, the two ships performed monitoring, collected evidence of infringements and conducted law-enforcement to safeguard the country's marine interests, according to the administration.