1 of 3
Natacha Pisarenko, Associated Press
A worker gestures beside an YPF oil company truck near a plant in La Plata, Argentina, Thursday April 19, 2012. Argentine President Cristina Fernandez has defended the move to re-nationalization of YPF as part of a drive to restore her country's sovereignty, increase oil production and rely less on hydrocarbon imports.

BUENOS AIRES, Argentina — Shares in Spain's Repsol company have tumbled 17 percent this week as Argentina shows no signs of backing down in its takeover of Repsol's controlling stake in Argentina's YPF energy company. There are also signs the government may pay far less than what Repsol says the shares are worth.

Spain is demanding full compensation and is seeking help from the World Bank, the International Monetary Fund and the European Union. But Argentine officials are shrugging off the criticism.

Economy Minister Hernan Lorenzino is in Washington to defend the nationalization at the annual meetings of the IMF and World Bank. He accuses Repsol of letting crude production drop by half since Argentina's state-owned energy company was privatized.