ANTI-TERRORIST police questioned up to a dozen Huddersfield University students in the wake of the July 7 London bombings.
Details of the inquiries were revealed today - hours after police released new images of the deadly bomb gang.
The Examiner understands the students were quizzed by detectives after their friendships with a number of the suicide bombers were uncovered.
Dewsbury's Mohammed Sadique Khan, 30, Shehzad Tanweer, 22, and Hasib Hussain, 19, from Leeds and former Rawthorpe High School student Jermaine Lindsay, 19, killed 52 people and injured hundreds more when they blew themselves up on London tube trains and a bus on July 7.
Police investigating the atrocities have appealed for help from the public as they try to piece together the build-up to the July 7 attacks.
Part of that work has involved probing the backgrounds of all four killers.
A university source said: "They were helping police with what they knew on a friendship level.
"They had known some of the bombers but had no idea what they were planning."
The massive investigation into the July 7 London bombings centred on four Yorkshire suicide bombers.
And as part of the inquiry, anti-terrorist officers quizzed University of Huddersfield students, it emerged today.
The police were trying to gather every scrap of information on the killers, who travelled south to London and murdered innocent passengers on three Tube trains and a bus.
Mohammed Sadique Khan, 30, of Thornhill Lees, Shehzad Tanweer, 22, and Hasib Hussain, 19, both from Leeds, and Jermaine Lindsay, 19, who went to school in Rawthorpe, killed 52 people and injured hundreds more when they blew themselves up on London tube trains and a bus on July 7.
The news of the investigations at the University campus comes in the same week as a prominent academic said extremists could be recruiting new members by targeting students - including those in Huddersfield.
The claim, by Professor Anthony Glees, is to be published in a report due out this week.
He says the extremists include Islamist Jihadists, animal rights activists and the British National Party.
Prof Glees said that every university in the UK needs to tighten up procedures to stop infiltration by extremist elements.
The Brunel University academic said, from the evidence collected in his study, there was no reason to believe any university was safe.
He said: "There is a culture of extremism and terrorism on Britain's campuses."
He told the Examiner: "Are these groups, which may support extreme or violent ends, operating officially or unofficially?
"At Huddersfield University, like other universities, there's no guarantee."
Last week education secretary Ruth Kelly told universities to watch out for extremists.
She said that after the terror attacks in London, universities should protect free thinking but inform police of "unacceptable behaviour" by students or staff.
Huddersfield University spokesman Phil Williams said they were aware of the threat from extremists.
He added: "We have never had any on campus.
"There was an issue of a Christian group which wasn't appropriate, but we worked with the student Christian group and chaplain and they never made it on to campus."
Mr Williams said they examined foreign student applications in detail.
He said: "There are bogus students coming to the UK, but it is slightly exaggerated.
"We check in detail and check qualifications to make sure there's no problems.
"We have never had an issue with any extremism on campus, but we are still wary of it.
"There is no room for complacency."
Meanwhile, the huge hunt continues. A dozen police officers in fluorescent jackets are still sifting through piles of stinking rubbish on a West Yorkshire waste site.
The men, who were wearing overalls under their jackets and white safety hats, appear to be systematically searching a small area of the rubbish heap at Skelton Grange, near Leeds, helped by two mechanical diggers.
One local resident said: "They've been here for weeks, dozens of them. They've been searching the same bit of rubbish every day it seems.
"The diggers skim off a layer at a time and then they move in and search it quite painstakingly."