Spanish oil major Repsol's board of directors voted unanimously Wednesday to reject a proposal by the Argentine government to compensate the company for last year's expropriation of most of its stake in Argentine oil firm YPF.

Repsol said in a regulatory filing that the offer was "unsatisfactory" and not in the company's interests, adding that the "amount did not correspond to the loss suffered by Repsol."

Under the proposal, which Buenos Aires valued at roughly $5 billion (3.82 billion euros), Repsol would have been given a 47 percent stake in a new company with rights to develop 6.4 percent of the vast Vaca Muerta shale formation in western Argentina.

According to the offer, that company would also comprise YPF, with a 51 percent stake; and Mexican state oil company Pemex, with a 2 percent interest.

In exchange, Repsol would have to drop a more than $10 billion compensation lawsuit.

Repsol's board, however, unanimously rejected the proposal after a "thorough internal technical and economic analysis" backed by "reports from outside specialists."

The analysis concluded that the offer consisted of "overvalued assets," adding that the Argentine government's valuations were "far removed from market values."

The Spanish company said the structure of the proposal did not come close to meeting Repsol's interests because it lacked available or realizable monetary compensation, did not include "minimum legal and economic guarantees" and implied "mandatory and substantial" investments.

Despite rejecting the offer, Repsol said it valued "the Argentine government's interest in negotiating a settlement" and trusted that it would remain "open to dialogue" in the future with a view to reaching an agreement.

The Argentine government seized control of YPF when lawmakers approved a bill in May 2012 to expropriate a 51 percent stake in the energy firm from Repsol, which retains a minority stake in the oil company.

President Cristina Fernandez's administration accused the Spanish company of using YPF as a cash cow to fund its international expansion.

The World Bank's International Center for Settlement of Investment Disputes agreed last December to hear a complaint filed by Repsol against the expropriation.

The Spanish company filed the suit on Dec. 3, six months after notifying Argentina that it planned to take the dispute to international arbitration unless it received fair compensation for its former Argentine unit.

The Spanish oil major is seeking to have the nationalization declared illegal and for Argentina to be forced to reverse the decision or compensate the company for it.

Repsol, which formerly had a 57.4 percent stake in Argentina's largest oil and gas producer but now holds a roughly 12 percent interest, is seeking $10.5 billion in compensation from the Argentine government.

The Spanish company also has taken legal action against the nationalization in courts in Argentina, Spain and the United States.