Over 1,000 volunteers Thursday joined in coastguard personnel and local authorities to clean up a huge oil spill in the sea in southern Indian state of Tamil Nadu.

The volunteers including local fishermen and engineering students queued to assist the official workers to take out thick sludge from the beach in Chennai, the capital city of Tamil Nadu. The volunteers were seen passing on sludge filled buckets to one another in a bid to clear the sea water of the oil spill.

Officials said workers switched over the manual cleaning after machines at the beach proved useless.

"The machines were pumping out water rather than the sludge that has accumulated on the surface of sea water," an official said. "So we are manually cleaning the sea using our hands."

Tons of oil spilled into the sea last week when two cargo ships collided off the coast of Chennai near the Kamarajar Port.

Media reports said around 70 tons of oil have spilled into the sea, out of which around 50 have been removed.

The clean-up operation is going on for the past three days and according to India's Coast Guard officials around 15 tons of oil and sludge have been collected.

"The Coast Guard coordinated with all stake holders and resource agencies including state pollution control board, district administration and other non-governmental organizations to expedite the oil slick clean-up due to collision," a statement issued by the Coast Guard said.

The Coast Guard helicopters are conducting regular sorties to monitor the areas affected with the spill.

Reports said the spill has triggered environmental concerns as it has resulted in death of turtles and fishes along the polluted parts of coastline from Kamarajar Port stretching up to several miles.

At Marina beach volunteers were seen lifting oiled sand with their hands, without using any protective gear, and collecting them in buckets and bags.

The oil slick floating on the water has prevented fishermen from going out into sea and get their daily catch.