FUZHOU -- Investigators are blaming poor visibility and an unqualified crew for Sunday's shipwreck that killed five people off southeast China's Fujian Province, the local maritime bureau said on Wednesday.

"Quanfeng 369", a Chinese cargo ship owned by the local Fengze Shipping Company Ltd., sank off Quanzhou city in Fujian on Sunday after colliding with "Xing'an", a ship registered in Nanjing, east China's Jiangsu Province. Only seven of its 12 crew members were rescued.

Rescuers had recovered five dead bodies by Tuesday night, said Zhou Honghui, an official with the Quanzhou municipal maritime affairs bureau.

Zhou blamed foggy weather for the collision. "Visibility was only 500 to 600 meters when the accident occurred."

Besides, the vessel "Xing'an" only had nine crew members instead of the 10 required for a ship of its size, he said. "Only three of the crew members held licenses -- even the captain didn't have the proper qualification."

Zhou said the maritime affairs bureau has started to salvage the sunken ship.

"We have worked out a detailed plan to prevent pollution, because 'Quanfeng 369' had 19 tons of diesel oil in its hold," he said.

The bureau is warning off passing ships from the salvage operation area.