BEIJING, Jan. 21 (Xinhua) -- Several oil slicks have been seen in the East China Sea, close to the location where an Iranian tanker sank one week ago, according to China's maritime authority.

The State Oceanic Administration (SOA) said in a statement Saturday that a 4-km-long, 400-meter-wide oil slick was sighted about 5 km southeast of the tanker's location.

Surveillance vessel and aircraft Saturday confirmed multiple oil slicks of different sizes to the northwest of the site.

Satellite data showed three oil slicks totalling about 200 square kilometers within the monitored area. The largest measured about 164.2 square kilometers.

The SOA will continue to monitor the situation and provide updates, it said.

The Panama-registered, Iranian-owned oil tanker Sanchi, carrying 113,000 tonnes of light crude oil, collided with the CF Crystal, a Hong Kong-registered bulk freighter, about 300 kilometers east of the Yangtze estuary on Jan. 6 and sank on Jan. 14.

The 32 crew members onboard the tanker -- 30 Iranians and two Bangladeshis -- were lost.