"Mr Papandreou is due to hold telephone talks with his counterpart, in which he will demand the immediate release of the crew and their return to Greece pending their hearing," spokesman Panos Beglitis told journalists.

Four Greek crew members of the MV Tasman Spirit, which leaked 28,000 tonnes of crude oil into Pakistani coastal waters on August 14, are under house arrest in a Karachi hotel, along with three Filipino sailors from the same ship.

A court hearing into their case has been set for October 19, according to Beglitis.

"We have already issued sharp diplomatic notes to Pakistan ... there is also coordination with Malta because the ship was under (the) Maltese flag," Beglitis told AFP on Friday.

According to media reports, the crew face criminal charges over negligence in navigation and endangering lives.

Pakistani authorities said they are claiming one billion dollarsmillion euros) in damages from the Tasman Spirit's Greek managers, Polembros.

The oil spill occurred in a rich tropical marine ecosystem area, home to extensive mangrove forests, Green and Olive Ridley sea turtles, dolphins, porpoises, beaked whales and several species of lizards and sea snakes.

TERRA.WIRE