Police chiefs are demanding the power to lock up terror suspects indefinitely, it has emerged.
Reopening the debate over detention without trial, the Association of Chief Police Officers (Acpo) called for some suspects to be held for "as long as it takes".
Acpo president Ken Jones said police were struggling to operate within the 28-day limit, stressing the global scale of terror investigations and the need to arrest suspects early.
"We are now arguing for judicially supervised detention for as long as it takes," he told the Observer.
"We are up against the buffers on the 28-day limit.
"We understand people will be concerned and nervous, but we need to create a system with sufficient judicial checks and balances which holds people, but no longer than a day necessary."
The idea is said to have been discussed with Prime Minister Gordon Brown, who has signalled his intention to re-visit the subject of detention without trial this year.
Mr Jones added: "The key point is that the police require an ability to undertake a professional and thorough investigation that is proportionate to the threat posed by international terrorism," he said.
"It must also be noted that one of the suggestions we are making is that any time period granted will be managed and scrutinised by senior members of the judiciary at regular intervals."
Shami Chakrabarti, director of human rights group Liberty, said: "We elect politicians to determine legislation and we expect chief constables to uphold the rule of law, not campaign for internment."
