London (CNN) -- Privacy activists in Britain reacted angrily Monday to government plans to expand security agencies' monitoring of Internet and phone use.
The government wants to let police and intelligence agencies monitor what numbers people phone, when, and for how long, and whom they e-mail, the Home Office said Monday.
It would not give them access to "the content of any phone call or e-mail, and it is not the intention of Government to make changes to the existing legal basis for the interception of communications," said the Home Office, which is responsible for domestic security.
The Home Office said the proposed new powers were vital "in certain circumstances to investigate serious crime and terrorism and to protect the public."
The government plans to introduce the new powers as soon as possible, the Home Office said, promising that the law would be "compatible with the government's approach to civil liberties."
The Open Rights Group has launched on online petition against the plan, the "Communications Capabilities Development Programme."
As of Monday, it said more than 13,000 people had signed pleas to government ministers saying "I do not want the government to try to intercept every UK e-mail, Facebook account and online communication."
The campaign group calls the plan "pointless, easy for criminals to encrypt and evade," and "illegal: mass surveillance would be a breach of our fundamental right to privacy."
The campaign group Liberty also attacked the plan, saying the previous government had abandoned a similar proposal.
"Proposals to stockpile our Web, phone and texting records were shelved by Labour. Now we see plans to recycle this chilling proposal," said Isabella Sankey, director of policy for the campaign group Liberty.
"Whoever is in government, the grand snooping ambitions of security agencies don't change," she charged.
She said the agreement between the Conservatives and Liberal Democrats to form the current government "explicitly promised to end unnecessary data retention and restore our civil liberties."
Video surveillance is already common in Britain.
CNN's Bharati Naik contributed to this report.