An international arbitration panel has reached a verdict in a dispute over Venezuela's nationalization of Exxon Mobil assets, Venezuelan sources said on Saturday, adding they saw the decision as favorable to the South American nation.

The sources declined to specify the total amount that Venezuela was ordered to pay.

Exxon Mobil in 2007 filed a claim with a World Bank arbitration tribunal seeking at least $7 billion in compensation for a heavy oil project that President Hugo Chavez nationalized in a broad wave of state takeovers.

A favorable verdict for Venezuela would be a victory for Chavez and the country's state oil company PDVSA, which had always described Exxon's compensation claims as wildly exaggerated. An Exxon representative was not immediately available for comment on the verdict.

Venezuela still faces outstanding arbitration claims by a range of companies including oil firm ConocoPhillips and Swiss cement-maker Holcim , cases that could force Venezuela to make large payments in the run-up to Chavez's October reelection bid.

Exxon Mobil in 2007 said it had invested around $750 million in the Cerro Negro heavy crude project, which was renamed PetroMonagas as part of the state takeover. It was one of four projects that were taken over that year in the vast Orinoco heavy oil belt, now considered one of the world's largest reserves of crude.

In 2008, Exxon won an injunction against PDVSA to freeze up to $12 billion in company assets, a ruling that was quickly overturned but sparked furious criticism by the Chavez government and further deteriorated relations between the two.

Venezuelan energy minister Rafael Ramirez has said the country does not expect to pay more than $2.5 billion for the combined total of the ConocoPhillips and Exxon Mobil arbitration claims.

ConocoPhillips was an investor in two Orinoco projects that were taken over at the same time as Cerro Negro. The two companies had in total asked for as much as $40 billion in compensation.

Oil companies have remained keen to invest in the Orinoco belt, with U.S. oil major Chevron and Spain's Repsol in 2010 signing investment deals for new multi-billion dollar projects there.

The socialist Chavez has nationalized broad swathes of the economy, taking over private assets in sectors ranging from telecommunications and mining to farming and oil services.

(Reporting by Marianna Parraga, writing by Brian Ellsworth)