Tokyo, Feb 2 (IANS): Greenpeace warned on Friday that traces of crude oil found on an island in southern Japan may have come from the Iranian oil tanker Sanchi, which sank after an explosion in the East China Sea last month.

Traces of oil found on January 28 in Takarajima, a Japanese island home ot just 100 inhabitants, were likely to have come from the stricken tanker, which exploded and sank 530 kilometres from Shanghai after colliding with a Hong Kong-flagged cargo ship and remaining adrift for days, Efe news reported.

Paul Johnston of the Greenpeace International Science Unit warned that cetaceans, birds and fish in the region were at high risk of exposure but added that the samples would have to be tested to confirm that they were indeed from the oil tanker.

New samples of oil were found on Thursday at the nearby island of Amami Oshima, scattered over 500 metres along the coast, raising concerns among fishermen in the region as it comes in the middle of the shellfish and octopus fishing season.

Greenpeace urged Japanese authorities to intensify monitoring and evaluate the scale of the accident and its possible impact as well as to implement measures to prevent more crude oil from reaching the Japanese coast.

At the time of the incident, Sanchi was carrying around 136,000 tonnes of refined petroleum condensate, which is very volatile and inflammable but also evaporates and burns rapidly.

Chinese authorities, which were continuing clean up operations, said on Friday that the oil spill area had been reduced to 30 square kilometres.

Environmental organizations fear that the oil spill could be one of the worst environmental disasters in recent years as the East China Sea is one of the richest and most productive marine areas on the planet.