Venezuela has given the world's biggest oil company, ExxonMobil, until the end of this year to enter a joint venture with the state.
Failure to do so will almost certainly result in Exxon losing its oil field concessions in the country, BBC World news reported.
Venezuela's socialist government has now signed new agreements with almost all foreign petroleum companies.
After months of pressure from left- wing leader Hugo Chavez most foreign oil firms working there have caved in.
They have agreed to hand over a controlling stake of their oil interests to the Venezuelan state.
This means that Venezuela, which has the world's largest petroleum reserves, now calls the shots in what the foreign guests can and cannot do.
In addition, the companies which have signed the new contracts - such as Chevron, BP, Shell and Total - will in future be presented with much higher tax bills by the government.
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Venezuela Delivered Ultimatum To ExxonMobil
Failure to do so will almost certainly result in Exxon losing its oil field concessions there
