Picture taken on Jan. 12 shows Chinese vessels performing rescue tasks on site.
Satellite images showed on Tuesday there was no visible oil slick on the surface of the East China Sea near a sunken Iranian oil tanker thanks to clean up efforts, according to government reports.
The State Oceanic Administration, China's maritime authority, took a remote sensing image in an area within a 50-kilometer radius of the site of the sunken ship and discovered no visible oil slick on Tuesday, according to a statement from the administration.
On Sunday, three oil slicks were seen.
The administration said it will continue to monitor the situation and provide updates.
An area of 107.2 square nautical miles had been cleaned up by Tuesday, the Ministry of Transport said.
A total of 71 vessels participated in the cleanup, including maritime law enforcement ships, professional rescue boats, safety vessels and cleanup ships, the ministry said.
Satellite data showed on Sunday three oil slicks totaling about 332 square kilometers within the monitored area. The largest measured about 328 square kilometers, according to the administration.
On Sunday, an oil slick 5.4 km long and 1.4 km wide was seen about 5 km northwest of the sunken vessel. On Saturday, an oil slick measuring 4 km long and 400 meters wide was seen about 5 km southeast of the site, according to the administration.
The Panama-registered oil tanker Sanchi, from Iran, carrying 111,300 metric tons of highly flammable condensate oil, collided with a Hong Kong-registered cargo ship at about 8 pm on Jan 6 some 160 nautical miles east of Shanghai.
The Sanchi had 32 crew members－30 Iranians and two Bangladeshis. Three bodies have been found, according to the ministry. The cargo ship's 21 crew members were rescued.
Four rescuers boarded the burning tanker before it sank on Jan 14 and recovered two bodies and the "black box".
"I was not afraid when I boarded the Sanchi. I am trained to rescue people, or at least recover their bodies," said Lu Jun, one of the four rescuers who boarded the tanker one day before it exploded and sank.
Lu, 50, from the Shanghai Salvage Bureau, is an experienced diver and rescuer who has participated in many search and rescue operations.