Britain's Home Office interior ministry said Saturday it was investigating reports that hacking group Anonymous had attacked its website over the government's plans to boost Internet surveillance.

Visitors to the ministry's home page were greeted with a message saying the service was unavailable due to a high volume of traffic, after Twitter accounts purportedly linked to the hacking group called for it to be targeted.

"We are aware of some reports that the Home Office website may be the subject of an online protest," a ministry spokesman said.

We have put all potential measures in place and will be monitoring the situation very closely.

"If a successful denial of service attempt does occur tonight, we will liaise with the technical team and update as necessary."

A message on the Anonymous Operations account on Twitter read: "TANGO DOWN - http://www.homeoffice.gov.uk For your draconian surveillance proposals! Told you to #ExpectUs!" The claim was repeated on the Anonymous UK account.

The British government came under fire earlier this week over proposals to allow the intelligence agencies to monitor calls, emails, text messages and website visits as part of its effort to tackle serious crime and terrorism.