Prime Minister Abdullah Ahmad Badawi has ordered an immediate investigation into the expulsion of national oil firm Petronas from Chad, reports said today.

Chad's President Idriss Deby Itno on Saturday ordered Petronas and US energy giant ChevronTexaco to leave the country from Sunday for what he said was non-payment of taxes, according to national radio.

Abdullah has ordered Petronas president Hassan Marican to lead the investigation by despatching a team to the African country, the New Straits Times said.

"I want Petronas to act fast as this is a very serious issue," Abdullah said in the report.

"I have told Hassan to find out in detail as to what transpired," he said. "This is a big surprise to me, (it is) unlikely for a credible company like Petronas to be dragged into such a controversy."

ChevronTexaco and Petronas are two of three members of a consortium extracting the central African country's oil resources.

Their departure would leave the US oil giant ExxonMobil and the Chadian government to tap the resources together "while waiting to find a solution with the two other partners", Deby said in a speech.

Petronas' responsibility

Abdullah said the Malaysian government would not be intervening in the case because it was Petronas' responsibility to resolve the matter.

"It's their own company and they should be able to get all the facts. They must act very fast because the warning is very serious," he said, according to The Star newspaper.

In a bid to increase Chad's share of its oil revenue, Deby on Wednesday told his government to renegotiate the contract it signed in 1988 with the US-Malaysian consortium.

On Saturday, Deby said three ministers involved in the deal would cease work and go before judicial authorities "to answer for their acts". He did not name the ministers and no further details were available.

Oil has been flowing since 2003 in the Doba basin in southern Chad. In 2004 Chad, which produces less than 200,000 barrels of oil a day, posted economic growth of 40 percent as oil exports began.