Chavez announced plans earlier this week for the state to take control of the country's largest telecommunications company, its electricity and natural gas sectors and four heavy crude upgrading projects now controlled by some of the world's top oil companies.
It had not been clear whether Chavez intended the state to have total control of the projects or a majority stake as his government had previously said.
In a speech to congress Saturday, Chavez said the private companies — British Petroleum PLC, Exxon Mobil Corp., Chevron Corp., ConocoPhillips Co., Total SA and Statoil ASA — would be given the option to stay on as minority partners.
"He who wants to stay on as our partner, we'll leave open the possibility to him. He who doesn't want to stay on as a minority partner, hand over the (oil) field and, goodbye," he said.
"Goodbye, good luck and thank you very much," Chavez added in English.
Chavez's government has already taken majority ownership of all other oil-producing operations in the country through joint ventures controlled by the state oil company. Most companies have shown a willingness to continue investing despite the tightening terms, which have also included tax and royalty increases.
Chavez, who was giving his annual state of the nation address, said the joint ventures, which were formed last year, have saved the government some $6 billion in costs.
Venezuela also increased royalties on the four Orinoco projects last year from 16.6 percent to 33.3 percent, a move Chavez said earned the government an extra $840 million in the second half of 2006.
Also on Saturday, Iranian President Mahmoud Ahmadinejad — at the start of a Latin America tour — was scheduled to meet with Chavez, whom Ahmadinejad described as a "brother" during his first visit to Venezuela in September.
Officials did not provide details on what he and Chavez have planned to discuss.
Chavez and Ahmadinejad have been increasingly united by their deep-seated antagonism to Washington.
Chavez has become a leading defender of Iran's nuclear ambitions, accusing the United States of using the issue as a pretext to attack a regime it opposes and promising to stand with Iran.
The two governments plan to build factories to produce everything from bricks to bicycles and have agreed to set up a $2 billion dollar investment fund.