Hanoi, July 26 -- Vietnam on Sunday thanked China for its assistance in search and rescue operations after a Vietnamese cargo vessel, sank in the South China Sea, with 45 of the 62 people on board rescued as search efforts continued for the remaining crew, according to Xinhua news agency.

The Vietnamese vessel, 'Khoi Nguyen 18', was carrying 62 people when it sank in unfavourable weather conditions near Yongshu Reef in the Nansha Islands in the South China Sea, Xinhua reported.

Chinese and Vietnamese rescue teams have mounted a joint operation involving multiple vessels and a rescue helicopter.

According to Xinhua, Vietnamese Foreign Ministry spokesperson Pham Thu Hang said Vietnamese authorities "launched rescue operations immediately...