New Delhi: Cyber-attackers who identified themselves as the "Pakistani Cyber Army" have hacked the website of India's premier police agency, officials said Saturday.

The website of the Central Bureau of Investigation (CBI) was hacked by programmers who left a message saying that the attack was in revenge for similar Indian assaults on Pakistani sites, Press Trust of India said.

The hackers signed their message on the Indian police website: "Long Live Pakistan."

CBI authorities said they were working to restore the site, which offered information to the public.

The spokeswoman said she could not comment on Indian media reports that more than 200 other Indian sites had also been attacked by Pakistani hackers.

"We came to know the CBI site had been compromised Friday night," the spokeswoman told AFP, asking not to be named. "It will take us a couple of days to restore the site."

The CBI was investigating the attack and could not immediately say who was responsible, she added.

The message posted on the CBI site said the attack was "in response to the Pakistani websites hacked by 'Indian Cyber Army'," the Press Trust of India said.

"Hacked hahaa funny," the message said. "Let us see what you investigating agency so called CBI can do" (sic).

Hackers had also infiltrated the server of the National Informatics Centre (NIC), which maintains most of the government's web sites, the Press Trust of India reported.

In August, a group also calling itself the "Pakistan Cyber Army" hacked into the website of independent Indian MP Vijay Mallya, a flamboyant liquor baron, who is also head of Kingfisher Airlines.

The group claims to have hacked a number of Indian websites in recent years, including India's state-run Oil and Natural Gas Corporation, in retaliation for Indian hackers accessing Pakistan sites.

Indian IT specialists have long lamented what they say is a lack of awareness about Internet security across the country, including in the corridors of power.