LONDON (Reuters) - Police in Britain can hold terrorism suspects without charge for longer than in any other comparable democracy, according to a study by human rights organisation Liberty.
Britain's 28-day limit already far exceeds other democracies and the government is considering doubling it.
Liberty staff interviewed terrorism specialists and lawyers in 15 countries. Their research found that in the U.S. the detention limit is two days, in France it is six, Italy four and in Turkey suspects can be held for 7-1/2 days.
In Spain, where 191 people died in the 2004 Madrid train bombings, there is a five-day detention limit. The closest any country comes to Britain's month-long limit is Australia with 12 days.
Liberty Director Shami Chakrabarti told BBC radio: "It's really quite astonishing, given this has been one of the most contested issues in British politics for two years now.
"Of course, many of these countries face very similar challenges from international terrorism to those (faced) here."
The survey comes as the government considers extending its detention limits.
Tony McNulty, minister for security, counter-terrorism and crime, told the BBC's Question Time last week: "In some cases, there may well be a need for police to go towards 56 days."
Chakrabarti said such a move would inevitably lead to injustice.
"Ministers have rightly lectured generals in Burma and Pakistan about their rights record, but human rights, like charity, begins at home," she said in a statement.
"Holding suspects for more than a month without charge would be an international embarrassment."
Police chiefs have consistently argued that Britain's month-long detention provisions are necessary to meet the unique challenges of terrorism. Investigations can often cross international borders, involving suspects with several aliases and speaking a variety of foreign languages.
However, Chakrabarti said long detention without charge was unnecessary.
"With safeguards, I think it's perfectly proper to charge someone with a lower-level terror offence ... while you continue to investigate a complex conspiracy to murder," she said.
(Reporting by Johanna Leggatt; Editing by Steve Addison)