Virgin Media has amended a clause in the terms and conditions for users of its London Underground Wi-Fi service, which went live last week, in response to complaints from privacy campaigners.

Originally, the T&Cs stated that Virgin Media “may monitor email and internet communications, including without limitation, any content or material transmitted over the services”.

The suggestion that Virgin Media could be snooping on customers' communications raised the ire of MPs and privacy campaigners alike, with conservative MP Robert Halfon suggesting that “a surveillance society is being created on the Underground”.

Virgin Media has now revised its language, stating that it “has the right to restrict access to any inappropriate content on the service,” and specifying that personal information will not be passed on to third parties unless it is required to do so for legal or regulatory reasons.

“We are not monitoring how individuals use our Wi-Fi service and have clarified our T&Cs to make this clear,” said Virgin Media in a statement. “We block illegal or harmful content in line with our legal and regulatory obligations.”

A company spokesperson insisted that this is not a U-turn, because Virgin Media never intended to snoop on customers. The clause was simply included to enable it to fulfil legal obligations to block certain content, such as illegal file-sharing sites like The Pirate Bay.

The spokesperson also said the company has a moral obligation to block things like adult content in public areas.

Virgin Media censors such websites by monitoring when a request is made to access an IP address that is known to contain illegal or adult content, and then blocking that request. This is standard practice across the industry.

Nick Pickles, director of privacy and civil liberties group Big Brother Watch, praised the company's decision to amend its T&Cs.

“Clearly such broad terms and conditions were a cause for concern and I’m pleased Virgin have moved quickly to address this serious privacy issue,” he said. “The public should be able to use Wi-Fi services without fear of their internet use and emails being monitored.”

Wi-Fi was turned on at several Tube stations including King’s Cross, Oxford Circus and Victoria last week, allowing commuters and visitors to get online while underground. Virgin Media hopes to connect 80 stations by the end of July, and 120 stations by the end of 2012.

Meanwhile, London Overground has signed a deal with The Cloud to provide free Wi-Fi to passengers at some 56 stations across the capital.