Updated January 15, 2018 19:43:18

The fire from a sunken Iranian tanker ship in the East China Sea has burned out, a Chinese transport ministry spokesman has said, although concerns remain about possible major pollution to the sea bed and surrounding waters.

The spokesman, who identified himself only by his surname, Zhao, said the fire ceased about noon (local time).

Earlier footage showed huge clouds of thick smoke rising from the oil slick.

Just three bodies from the tanker Sanchi's crew of 32, composed of 30 Iranians and two Bangladeshis, have been recovered.

The cause of the January 6 collision between the Sanchi and the Chinese freighter CF Crystal, which happened 257 kilometres east of Shanghai, remains unclear.

All 21 crewmembers aboard the freighter were reported safe.

Rescuers boarded the Sanchi on Saturday morning (local time) to recover two bodies, but a large explosion shook the ship around noon on Sunday and it sank within hours.

High temperatures had prevented rescuers from entering the crew quarters.

Photo: The hull of the tanker exploded, Chinese state media reported. (Reuters: China Daily)

The ship was carrying a type of hydrocarbon liquid known as natural gas condensate and left a 10-square-kilometre area contaminated with oil, according to Chinese authorities.

Condensate is highly toxic but readily evaporates or burns off in a fire. If trapped underwater, however, it could seriously harm the marine environment, while the ship's fuel source also poses a major threat.

The ship's voice data recorder, which functions like a "black box" on aircraft, was reportedly recovered on Saturday (local time), possibly helping shed light on how the collision and resulting fire occurred.

Mr Zhao, who is deputy head of the ministry's press office, said new photos and video footage showed the fire had gone out entirely and said an investigation into the disaster would be conducted according to the "strictest international standards".

Photo: Friends and colleagues gather at the headquarters of the National Iranian Tanker Company in Tehran. (AP: Vahid Salemi)

Chinese state broadcaster CCTV said rescue operations had been converted at noon to a search-and-recovery effort.

Two ships were on the scene spraying foam detergents to dissolve oil remaining on the surface.

The Government also announced Monday as a nationwide day of public mourning over the disaster.

Photo: The oil tanker caught fire after a collision with a Hong Kong-registered freighter off China's eastern coast. (AP: Korea Coast Guard)

AP

Topics: maritime, disasters-and-accidents, china, iran-islamic-republic-of

First posted January 15, 2018 19:29:29