She would also investigate allegations that TotalFinaElf did not do enough to limit pollution after the tanker broke in two and sank off western France, spewing out 15,000 tonnes of oil.

Such an investigation is a step short of formal charges and can end without charges being brought.

TotalFinaElf rejected the accusations, saying it was not warned the ship was unsafe and therefore the security lapse was not its fault. It also said maritime authorities, not the company, should have worked to limit pollution.

The company said its group director and five other employees had been called for questioning and may themselves personally be placed under formal investigation.

The Maltese-registered tanker sank in a storm off the rocky coast of Brittany in December 1999, unleashing an oil slick that ravaged close to 400 km (250 miles) of coastline.

"TotalFinaElf intends to show that the company and its employees did not contribute in any way to the accusations laid against them," the company said in a statement.

The decision to launch a probe follows the completion last month of an investigation by judicial experts into the accident.