BUENOS AIRES, Nov 17: Bombs exploded at three banks in the Argentine capital on Wednesday, including two branches of U.S. giant Citibank, killing one security guard and injuring a bomb squad officer, officials said.

It was not clear who was responsible for the bombs, none of which were big enough to cause major damage to buildings. "The government is asking the people not to touch any packages and to call the police if they find them. Everything is being investigated," an Interior Ministry spokesman said.

Several foreign-owned banks and even a march by unemployed protesters have been hit by small bombs in the last three years. No group claimed responsibility for any of them.

The last time Buenos Aires' banks were targeted by small bombs was during the August visit of International Monetary Fund chief Rodrigo Rato. No one was injured in those.

In the first Citibank explosion in a middle-class district, the bomb killed a private security guard before the bank opened to the public. At the second Citibank blast, in a posh shopping area, police detonated the device and a bomb squad officer was injured while protecting a woman who broke through the police cordon, federal police said.

A third explosion hit Argentine bank Banco Galicia but a bank official said there were no injuries. Citi group officials in Buenos Aires and New York were not immediately available for comment.

In the wake of Argentina's economic collapse in 2002, many Argentines blamed banks - foreign and local - for their country's woes, including a freeze on their savings. But that ire had waned as the economy recovered and people got back their money.

Foreign heads of state were on Argentine soil on Wednesday. Chinese President Hu Jintao was in Buenos Aires on a two-day state visit, while the King and Queen of Spain were attending a language conference in Rosario, 400kms north of Buenos Aires. Financial markets in Argentina and abroad had no negative reaction to the string of bombings. -Reuters