Image caption Control orders were introduced under the former Labour government in 2005

The coalition plans to replace control orders with a new range of restrictions to keep terror suspects under surveillance, the BBC has learned.

One working title for the new curbs is "surveillance orders".

They would restrict suspects' movements but end overnight curfews and a ban on mobile phones if numbers were supplied.

Labour said the plans, a source of tension within the coalition government, were driven by politics not the public interest.

Introduced under the former Labour government in 2005, control orders allow ministers to place a terrorism suspect under close supervision that some say is similar to house arrest.

Opponents say this infringes civil liberties, but supporters argue it is necessary to protect the public. The Lib Dem manifesto pledged to get rid of the "house arrest" element.

Travel ban

Ministers have been locked in talks over what should replace control orders after Prime Minister David Cameron said they had not been a success.

The BBC understands the new orders would give the security services the power to:

ban suspects from travelling to locations such as open parks and thick walled buildings where surveillance is hard

allow suspects to use mobile phones and the internet but only if the numbers and details were given to the security services

ban suspects from travelling abroad

ban suspects from meeting certain named individuals, but limited to people who are themselves under surveillance or suspected of involvement in terrorism

Under the planned new orders, the security services would lose the power to impose overnight curfews, force suspects to phone into a monitoring company every time they entered or left their homes and lift the ban on them using mobile phones and the internet.

They would also lose the power to force suspects to live in a particular location, known as "relocation orders", or limit the visitors to their homes.

Tagging

However, one detail that appears to remain unresolved is over the future of tagging.

This will no longer be used to enforce a curfew by informing the authorities whether or not a suspect is at their home.

But some in government are pushing for the security services still to have the power to tag suspects simply so they can keep tabs on them by knowing if they are no longer sleeping regularly at one particular address.

This is a chaotic and disorderly way in which to decide national security policy Ed Balls, Shadow home secretary

The BBC has also learned that the government is drawing up tough new anti-terror laws that could be rushed through Parliament after a major terrorist incident - in case the new surveillance orders proved inadequate in the face of increased threat levels.

Whitehall sources said the draft legislation would - if enacted - give the police and the security services effectively the same powers they have now under existing control orders.

The so-called Terrorism Prevention Orders would be put before Parliament if the heads of the three intelligence agencies and the home secretary agreed there was a national emergency.

Downing Street said the Cabinet gave its "broad agreement" to the changes that will be made to control orders during a meeting on Tuesday.

It follows weeks of heated negotiations between the coalition partners over the proposals, with reform of the existing system regarded as non-negotiable by the Liberal Democrats.

'Chaotic'

Speaking earlier this month, David Cameron said control orders "haven't been a success" but there needed to be a "proper replacement".

But shadow home secretary Ed Balls said that the process had "descended into a shambles" as ministers struggled to find a way of keeping the coalition united.

"With daily leaks, briefings and counter-briefings, this is a chaotic and disorderly way in which to decide national security policy," he said.

"It is deeply regrettable that the future of control orders has become first and foremost about a political negotiation, or a 'deal' as Nick Clegg described it last week, to keep the coalition together rather than exclusively about what is in the national interest."

The terrorism review has still to be examined by the independent reviewer, Lord Macdonald, and so it is unlikely to be published for a couple of weeks.