Six days after the oil spill off Chennai coast, over 2,000 personnel from different agencies on Friday stepped up clean up efforts even as the Coast Guard believed it may take at least 10 days to clear the sludge from the site of collision of two ships in Ennore port.

Coast Guard Eastern region Inspector General Rajan Bargotra while giving details of the clean up said a probe has been ordered by the Directorate General of Shipping into the oil spillage that has blackened the Chennai shoreline following the collision of two ships last Saturday.

Describing the incident as a "major accident but a minor (oil) spill," Bargotra said "oil spill has occurred in nearly 34,000 square metres in the Eastern coast of Bay of Bengal" amid reports that marine life has been affected.

Volunteers wearing gloves could be seen scooping up the thick tar with shovels off Kamarajar Port, formerly Ennore Port.

The mishap occurred at about 4 am when 'M T BW Maple', with a flag of 'Isle of Man', was leaving after emptying Liquefied Petroleum Gas and M T Dawn, Kanchipuram, loaded with petroleum oil lubricant (POL), was on its way to berth at the Kamarajar Port.

"Oil spill has occurred in nearly 72 km off the eastern coast from Ennore Port to Mahabalipuram. About 12 km got affected with oil slick and about 250 metres particularly in R K Nagar Kuppam area was most affected," he told reporters on board a Coast Guard ship in Bay of Bengal.

Noting that 72 tonnes of oil sludge has been collected, he said, 54 kilolitres of oil mixed with water was collected through super sucker equipment.

"An inquiry has been ordered by DG Shipping and based on that we will be able to know exact amount of oil spilled into the sea on the day of the incident," he said.

Stating that by tomorrow evening, the coasts of Marina beach and Elliots Beach at Thiruvanmiyur would be cleaned, he said it would take at least three or four days to clean up the South coast area which was affected.

"At least 10 days will be needed to clean the Ennore Port area (where the incident had occurred)," he said.

Chennai Port Trust Chairman P Raveendran said scientists from IOC Faridabad, Petroleum Ministry Additional Secretary, Joint Secretary, Ministry of Shipping have already arrived to take stock of the situation.

He said an inquiry has been ordered under Captain Subhash Kumar to identify the cause of the mishap.

Bargotra later said 2,600 personnel from various agencies along with Coast Guard, Tamil Nadu Police Coastal Security Group, Pollution Control Board, Fire and Rescue Department, State Highways, Chennai Port Trust, Chennai Corporation, volunteers from various colleges, universities and NGOs are involved in the cleaning operations.