Preparations are under way to send a robot submarine to explore a sunken Iranian oil tanker where all 32 crew members are believed to have died, Chinese officials said.

Larger salvage vessels and divers will also be sent to support the operation, which could see holes plugged in the Sanchi, the Shanghai Maritime Search and Rescue Centre said.

The tanker is lying under 377ft of water in the East China Sea. It caught fire after colliding with a freighter on January 6 before exploding and sinking on Sunday about 330 miles south-east of Shanghai.

The report said an expanding slick from the Iranian-registered ship’s cargo of natural gas condensate is being monitored for potential environmental damage, with clean-up efforts being organised.