A group of Brazil-based hackers took down the main corporate Web site of New York-based Citigroup on Friday, as the loosely associated collective continued its weeklong campaign of attacks on Web properties of major international banks. The public site of Brazil's central bank was also taken down.

The attack on Citigroup's Web site, which did not affect the bank's U.S. consumer portal, came as part of a seemingly coordinated barrage against banking sites Friday that also affected the Brazilian banking federation and Brazilian financiers Banco BMG and Banco Panamericano.

A day before, hackers in Brazil targeted the Web site of London-based HSBC

Earlier in the week, hackers saying they belonged to the Brazilian branch of the worldwide "Anonymous" cyber movement claimed responsibility for attacking the Web sites of major Brazilian banks Bradesco, Itau and Banco do Brasil. 

The hackers told Brazilian economic daily "Valor" they were taking the action as a way of protesting the "countless inequalities in the country," according to French news agency Agence France Presse.

According to the Dow Jones Newswires, the group used its Twitter account to publicize the attacks and has published a hit list of institutions it will target in the future, including airlines, telephone companies, credit-card companies, and government Web sites.