NSG sources said that cyber criminals hacked the official website - www.nsg.gov.in - on Friday, Jul 1 and corrupted some of the official domains of the force.
The website domain has not suffered much damage and a technical probe has been initiated to identify the source of the attack which could have possibly existed outside the country, they said.
Officials said that they are working to fix the issue and ordered a probe to look into the matter.
"We are yet in the process of identifying the extent of damage. A probe has been launched to identify the hackers, who tried to breach the security. We will soon identify them. There is also suspicion that the attempt was made to deface the website by some foreign agency," said a senior NSG official
Anyhow, NSG spokesman rejected the report of confidential data breach and said that the hack was done by government agencies of India to check vulnerability of the site.
"The problem was detected on Friday... and we have ordered upgradation of security features on our site. There was no loss of crucial data. It was done by government agencies of India to check vulnerability of our site," NSG spokesperson said.
Earlier, the hacker group Anonymous hacked the website of National Informatics Centre (NIC INDIA) and posted their logo along with a message to Prime Minister Manmohan Singh.
Similarly, some unknown hackers attacked Congress General secretary Rahul Gandhi's website and two servers created by him for family constituencies in UP. The hackers illegally accessed the password and tweaked the internet address to redirect users to an engineering college website.
In Dec 2010, Pakistani cyber attackers hacked CBI website and left a note saying "Pakistan Zindabad". Hackers claimed that the attack was in response to a cyber attack by Indians on Pakistan websites.