|More than 3,600 Indian websites were reportedly hacked in the first six months of this year [GALLO/GETTY]
Cyber-hackers calling themselves the "Pakistani Cyber Army" have compromised the website of India's top police agency and issued a warning message to Indian hackers, an Indian news agency says.
The Central Bureau of Investigation (CBI)'s site was shut down on Friday by hackers who posted a message saying that it was done in revenge for similar Indian assaults on Pakistani websites, the Press Trust of India [PTI] said.
CBI authorities say they are working to restore the site as they investigate who was responsible for the attack.
The group of hackers has warned it would carry out the "mass defacement" of Indian websites, the news agency said on Saturday.
"CBI registered a case for the defacement of its website...It has come to the notice of CBI that its official website was unauthorisedly accessed and deface," it added.
The message posted on the CBI site said the attack was "in response to the Pakistani websites hacked by 'Indian Cyber Army'," PTI reported.
"Hacked hahaa funny," it said. "Let us see what you investigating agency so called CBI can do".
Hackers had also infiltrated the server of the National Informatics Centre (NIC), which maintains most of the Indian government's websites, PTI added.
The "Pakistani Cyber Army" claims to have hacked a number of Indian websites in recent years, including India's state-run Oil and Natural Gas Corporation, in retaliation.
Indian information technology specialists have long criticised what they say is a lack of awareness about Internet security across the country, including in the corridors of power.
Sunil Abraham, executive director of the Bangalore-based Centre for Internet and Society, said it would have been easy for attackers to get into the CBI public site as it was "not a particularly sensitive" one.
'Lack of awareness'
The Indian government "has a very low level of cyber awareness and cyber security. We don't take cyber security as seriously as the rest of the world," he said.
He added that the government needed to "make at least 10 times the current level of investment to get their standards to match the rest of the world".
According to the Indian Computer Emergency Response Team [ICERT], a government agency that tracks IT security issues, more than 3,600 Indian websites were hacked in the first six months of this year.
An ICERT spokeswoman said she could not immediately say who was responsible for the attack.
The CBI website hacking came as the two nuclear-armed rivals continue efforts to repair relations that were cut off after the 2008 Mumbai attacks, in which armed men, whom India claimed were members of a Pakistani group, went on a shooting rampage in the financial district killing around 173 people.