KUALA LUMPUR - At least six Malaysian government websites were hacked into overnight after the Internet vigilante group Anonymous threatened to punish the authorities for censorship.

Sites that were targeted included the government's online portal, and the webpages of the information ministry , the fire and emergency services department and the land public transport commission .

Anonymous had warned it would attack the Malaysian government's online portal from Wednesday 1930 GMT to teach the country a lesson for censoring whistle-blower site WikiLeaks in an attack codenamed "Operation Malaysia".  

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Malaysian police chief Ismail Omar said he did not believe any personal or financial data had so far been stolen.

But he told Reuters: "It is too early to say what is the extent of the damage."

Newspapers reported that several other government websites including the construction development board had earlier been attacked. The sites appeared to be functioning early on Thursday.

It was not immediately clear if the attacks were launched by Anonymous or other hackers.

Anonymous is a grouping of global activists lobbying for Internet freedom who frequently try to shut down the websites of businesses and other organisations that they oppose.

Malaysia could be the latest target in a cyber-war waged by the activists, who gained prominence when they temporarily crippled the websites of MasterCard and Paypal that cut off financial services to WikiLeaks.

A spate of cyber attacks on multinational firms and institutions, from the US Central Intelligence Agency to Citigroup to the International Monetary Fund, has raised concerns that governments and the private sector may struggle to defend against hackers.  

In an earlier posting on pastebin.com, Anonymous had said Malaysia's censorship of films and television shows and its blocking of file-sharing websites amounted to a denial of human rights.  

Malaysia's industry regulator Malaysian Communication and Multimedia Commission last week banned 10 file-sharing sites and ordered Internet service providers like Telekom Malaysia and Maxis to block access.