As the debate over pre-charge detention returns to Parliament, Liberty has said that British police can already hold terror suspects for longer than comparable countries.

A survey of 15 countries released on Monday showed that Britain's 28-day limit for holding terror suspects without charging them was the highest.

The government has called for a consultation on options including doubling the period of pre-charge detention to 56 days.

However, some backbench Labour MPs, as well as the Conservatives and Liberal Democrats, have said they have not seen evidence that such moves were justified and pledged to vote against them.

Ministers say police may need more time to gather evidence in complex terror cases, but the Liberty study found that detectives in France were given six days and those in Turkey, seven-and-a-half days.

Former prime minister Tony Blair suffered his first Commons defeat after trying to increase the limit to 90 days.

And Liberty director Shami Chakrabarti told the BBC Radio 4 Today programme that many of the countries in the survey "face very similar challenges from international terrorism to here".

"Spain suffered the Madrid bombings, they have five days, and there wasn't a great big row about pre-charge detention there," she said.

Chakrabarti called on ministers to introduce alternative methods, such as charging suspects with lesser crimes to continue investigating more and serious offences.

"It's really quite astonishing given that this has been one of the most contested issues in British politics for more than two years now," she added.

Downing Street said every country "has to take decisions in its own national interest".

"Any extension beyond 28 days would have to be accompanied by extra judicial and parliamentary safeguards," the prime minister's official spokesman said.