Talking on state-run radio on Saturday, Idriss Deby, the president of Chad, asked both the companies to leave the country for refusing to pay taxes:
"Chad has decided that as of tomorrow [Sunday] Chevron and Petronas must leave Chad because they have refused to pay their taxes."
The president gave the oil production consortium that is led by Exxon Mobil, a deadline of just 24 hours to start making plans to leave.
Neither Kuala Lumpur-based Petroliam Nasional Berhad (Petronas) nor the California-based Chevron immediately commented on Derby's declaration.
The decision came a day after Deby ordered his government to take a greater role in the production of oil, which is viewed as a way to improve the country's ailing economy.
On Friday, Hourmadji Moussa Doumgor, a Chad government spokesman, told reporters that Deby wanted greater profits from oil production.
Deby has stressed that the country "should fully enjoy its oil, mining and other resources," Doumgor said.
Chad's oil revenues will be used
to reduce poverty
Chad is in the midst of setting up a national oil company and Deby has said that Chad would take responsibility for the oil fields that the American and Malaysian companies have overseen, which accounts for 60% of the country's oil production.
From October 2003 to December 2005, the consortium exported about 133 million barrels of oil from Chad, according to information compiled by the World Bank.
Chad itself earned $307 million, or about 12.5% on each barrel exported.
Not a member of Opec, Chad is one of Africa's newest oil producers.