"After investigation we have ruled out any threat of a
terrorist attack by these men," a police spokesman said, adding the three had been freed during Friday night.

According to the police spokesperson, the three men were overheard by what is being referred to as a "credible source" at the Holstenstrasse bus stop near a local railway station in the Altona district of the city. The witness told police he heard one of the men use the phrase "Tomorrow we will stand as heroes before Allah" before the three suspects boarded a bus heading away from the city center.

Hamburg police chief Reinhard Chedor said he was convinced that the men, aged from 21 to 25, were the suspects caught on film by a surveillance camera boarding a bus in Hamburg on Wednesday. He said one of the men was arrested and the other two had turned themselves in.

Control points and searches paralyze city

More than 1,000 police officers mounted an operation to set up road blocks and apartments and other buildings were searched.

The city's interior minister Udo Nagel admitted that the size of the police operation was dictated by fears of attacks similar to those on three underground trains and a bus in London last month which killed 56 people, including the four suicide bombers.

A police statement on Thursday revealed that the information regarding the operation was withheld from the public domain for 24 hours as not to jeopardize the initial criminal investigation.

Suspects caught on CCTV

The police also revealed that the suspects had been caught on close-circuit TV cameras and that their pictures were distributed as part of the ongoing search and investigation into their whereabouts.

The operation is the result of the latest in a long line of terror alerts that Hamburg has endured in the four years since it was revealed that the city was the home of a group of radical Arab students led by Mohamed Atta, the hijack pilot who crashed the first plane into the World Trade Center in New York on Sept. 11, 2001.

Terror trials in Hamburg

At the beginning of 2004, there was a tip-off concerning a possible attack on the armed forces hospital in Hamburg-Wandsbek. The area was evacuated and the hospital and surrounding streets searched for explosives. Nothing was found. Patients, visitors and local residents endured a further two weeks of controls and checks before the all-clear was given.

Hamburg has also been the center of the most high-profile terror trials in recent history with Moroccan's Mounir El Motassadeq and Abdelghani Mzoudi both appearing before courts in the city for alleged involvement with the Hamburg cell.

Mzoudi was acquitted and soon fled to Morocco after being threatened with deportation but El Motassadeq was found guilty of belonging to a terrorist group last Friday and was sentenced to seven years in jail. He was acquitted on a second charge of abetting mass murder.