The government said it acted on Saturday to take over the Jusepin oil field, which produces 33,000 barrels a day, from Total and the Dacion field (50,000 barrels) from ENI, after it failed to agree to a deal with the two firms which would give it a majority stake in new ventures.
The move came a day after the government adopted a new law on foreign oil companies that imposed higher royalties and profit taxes, as part of a new operating accord with Petroleos de Venezuela SA.
Oil Minister Rafael Ramirez said the European companies were among those which did not sign the new accords.
"Since April 1, all the oil fields that were under operating contracts have been placed under PDVSA control," Mr Ramirez said on state television.
"We are waiting for a resolution with [Total and ENI] after they exhausted the possibility of entering into the mixed companies," he said.
Takeover "illegal"
The new law changes 32 exploration contracts with foreign firms who must now enter into deals in which PDVSA has at least 60 percent control.
Venezuelan President Hugo Chavez has been working to strengthen state control over the country's oil production, and last year declared the 32 deals illegal, prompting the contract changes.
The new mixed companies must pay 30 percent royalties on the oil produced -- up from one percent -- and a 50 percent profit tax which has been increased from 36 percent.
ENI has vowed to fight the takeover, describing it as illegal.
"ENI believes that this action by PDVSA is a violation of ENI's contractual rights," it said in a statement, adding that it is considering taking legal action, and will seek compensation.
Total confirmed the takeover but refused to comment.
Sixteen companies have signed the accords: Chevron and Harvest of the US, BP of Britain, Anglo-Dutch giant Shell, Repsol of Spain, CNP of China, Petrobras of Brazil, Teikoku of Japan, Compania General de Combustibles (CGC) and Tecpetrol of Argentina, independent European firm Perenco and local firms Suelopetrol, Vinccler Inemaka and Open.
ExxonMobil, the world's biggest oil company, refused to accept the conditions and sold its shares in Venezuelan oil fields to partners.
Companies refusing to sign the new deals argue that they have pumped millions into Venezuelan operations and now may not see a return.
Venezuela is currently the world's fifth biggest crude oil exporter.
As well as the control demands, Venezuela is demanding more taxes from oil firms.
BP was last month slapped with a back tax bill of US$61.4m, and Total was told to pay US$108m.
ENI refused to pay, and $46 million was seized from its accounts on March 24 following a court order.