nationalization of YPF

MADRID (Reuters) - An incensed Spain threatened swift economic retaliation against Argentina on Tuesday after it announced plans to seize YPF, the South American nation's biggest oil company, in a move which pushed down shares in Spanish energy giant Repsol, the controlling shareholder.

Madrid called in the Argentine ambassador in a rapidly escalating row over the nationalization order by Argentina's populist and increasingly assertive president, Cristina Fernandez, a move which delighted many of her compatriots but alarmed some foreign governments and investors.

Promising action in the coming days, Spanish industry minister Jose Manuel Soria said: "With this attitude, this hostility from the Argentine authorities, there will be consequences that we'll see over the next few days. They will be in the diplomatic field, the industrial field, and on energy."

"Argentina has shot itself in the foot," said Foreign Minister Jose Manual Garcia-Margallo.

Despite the rhetoric, Spain appeared to have little leverage over Buenos Aires - any action to be taken will be determined at a cabinet meeting on Friday - and Argentina has proven impervious to such pressure in the past.

Repsol said YPF was worth $18 billion as a whole and it would be seeking compensation on that basis, but the Spanish oil major's shares fell by 7.5 percent in Madrid on Tuesday. The company said it could raise money in the bond market and sell some assets to help its cash flow.

Repsol described Argentina's move as "clearly unlawful and seriously discriminatory" and said it would take legal action.

"This battle is not over," Repsol Chairman Antonio Brufau said. "The expropriation is nothing more than a way of covering over the social and economic crisis facing Argentina right now."

But Fernandez dismissed the risk of reprisals. "This president isn't going to respond to any threats ... because I represent the Argentine people. I'm the head of state, not a thug," she said.

European Commission President Jose Manuel Barroso said he expected Argentina to uphold international agreements on business protection with Spain. "I am seriously disappointed about yesterday's announcement," he said in Brussels.

But action against Argentina appeared limited in scope. The EU Trade Commissioner would write to Argentina's trade minister to "reiterate our serious concerns" while an EU-Argentine meeting this week would be postponed.

"It's absolutely shameful considering everything that Spain has done for Argentina," said a woman called Domi, who was filling her tank at a Repsol petrol station in Madrid.

"I hope the government takes measures and does something serious. They've pulled our leg long enough!"

Spanish media condemned the Argentine action, believed to be the biggest nationalization in the natural resources field since the seizure of Russia's Yukos oil giant a decade ago.

La Razon newspaper carried a photograph of Fernandez on its front page in a pool of oil with the headline: "Kirchner's Dirty War", referring to her full name. The business newspaper La Gaceta de los Negocios called the takeover "an act of pillage".

El Periodico spoke of "The New Evita", pointing out that Fernandez had announced the nationalization in a room decorated with a large portrait of Eva Peron, the actress who was married to a president and revered by many Argentines as a populist mother of the nation and champion of the poor.

Repsol's Brufau said he suspected nationalization of YPF was imminent when he tried to contact Fernandez last Friday and was told that the president "was angry" and did not want to speak.

YPF has been under pressure from Fernandez's centre-left government to boost oil production, and its share price has plunged in recent months on speculation about a state takeover.

Spanish investment in Argentina may now be at risk after the move on YPF. In the "reconquista" or reconquest, of the 1990s, newly privatized Spanish businesses bought Latin American banks, telephone companies and utilities, much as their armor-clad ancestors had conquered the region 500 years earlier.

Through its latest nationalization move, Argentina runs the risk of frightening off foreign investors, key to contributing money to help develop one of the world's largest reserves of shale oil and gas recently discovered in the Vaca Muerta area.

ACE UP ITS SLEEVE?

This led some analysts to question whether Argentina might have an ace up its sleeve in the form of a new partner such as China Petrochemical Corp (Sinopec Group).

Repsol has, however, identified Vaca Muerta as "the cause of the pillage", or the reason Argentina went after its YPF share.

A Chinese website said Sinopec was in talks with Repsol to buy YPF for more than $15 billion, although other sources said the nationalization move would probably get in the way of such a deal. Sinopec dismissed the report as a rumor.

Fernandez said the government would ask Congress, which she controls, to approve a bill to expropriate a controlling 51 percent stake in YPF by seizing shares held exclusively by Repsol, saying energy was a "vital resource".

"If this policy continues - draining fields dry, no exploration and practically no investment - the country will end up having no viable future, not because of a lack of resources but because of business policies," she said.

YPF's market value is $10.6 billion, although an Argentine tribunal will be responsible for valuing the company as part of the takeover. Central bank reserves or state pension funds could be used for compensation.

Fernandez, who still wears the black of mourning 18 months after the death of her husband and predecessor as president Nestor Kirchner, stunned investors in 2008 when she nationalized private pension funds. She has also renationalized the country's flagship airline, Aerolineas Argentinas.

Such measures are popular with ordinary Argentines, many of whom blame free-market policies such as the privatizations of the 1990s for the economic crisis and debt default of 2001/02.

Her announcement of the YPF takeover plan, however, drew strong warnings from Spain, Mexico and the European Union, a key market for Argentina's soymeal exports.

Mexico's President Felipe Calderon said Fernandez's plan would damage chances for future foreign investment in Argentina and hurt Repsol, in which Mexico's state oil monopoly Pemex holds a 10-percent stake.

Venezuela, where socialist President Hugo Chavez has nationalized almost all the oil industry, applauded her move.

The row over YPF comes as Fernandez heaps pressure on Britain over oil exploration off the Falkland Islands, over which Argentina claims sovereignty.

(Additional reporting by Andres Gonzalez in Madrid, Tom bergin in London, Karina Grazina, Juliana Castilla and Hugh Bronstein in Buenos Aires, and Daniel Wallis in Caracas; Writing by Giles Elgood)