Sneak thieves launched an audacious daylight raid on valuable works of student art - as part of an elaborate exam scam.

The raid has seen a string of Bradford students lose works of art they had sweated months over - with some paintings carefully sliced out of their frames with scalpels.

Now college bosses are warning other lecturers around the country to be on their guard against students trying to pass off the work as their own amid a rising tide of plagiarism.

The students have been left stunned by the raid on their end of course art show at Bradford College's new Yorkshire Craft Centre - and fear the crooks could come back for more.

Lloyd Robinson, who had a one-off, hand-illustrated children's book, worth £600 stolen, said: "I am really depressed that someone had the nerve to actually do this.

"I think it is down to the lack of security, there are lots of exits but they only man those at the front. Anybody could just have walked in."

Art and design student Ben Morris, who lost six months work when his dissertation was taken, suspects foul play from students at other colleges.

Now their victims are circulating details of the missing art work and dissertations to other art schools.

The thieves are expected to use it at admission interviews to try to con their way onto college courses or impress their own tutors with high-quality work.

"I think it is the only reason why anybody would steal it because it has got no value to anyone else otherwise," Mr Morris said.

Tutors have admitted that plagiarism is a growing problem but warn the thieves are likely to be discovered if they try to pretend the work is their own.

Course leader in design at Bradford College, Will Godfrey, said: "As plagiarism increases colleges and universities take more steps to catch people," he said.

"Sometimes it is evident if the general standard of work is really rather poor and then you have one or two brilliant pieces. You can spot it by questioning students about their work, it is obvious if they can't explain how they got to the final piece.

"Increasingly people want to see back up work and if students can't provide that material it is unlikely that they would be taken on."

He said there was also a trend towards students buying essays from internet sites specialising in helping cheats.

But anyone trying to attempt that with the stolen dissertations would be "pretty stupid" as the work could easily be traced, he said.

Now the Bradford students are worried that more pieces will be stolen and have taken some of their most valuable work off display.

European textiles student Candice Small, who had a computer generated image taken, said: "It is my chance to impress people from industry who come to see my work but I am having to hide things."

Deputy head of Bradford College's school of art and design, Simon Thorpe, said the college would be speaking to the students and looking at ways to strengthen security.

"It is so disappointing that some people cast a shadow over the success of the summer exhibitions," he said. "Fortunately the students will have already been assessed and they will not be academically disadvantaged by the theft, upsetting though it is."

A West Yorkshire Police spokesman said: "Our enquiries are still at an early stage but it is possible that we will be speaking to other colleges about this. We would appeal for any witnesses to come forward."

Any witnesses who saw pieces of art work being carried out of the college building on Carlton Street on Friday or Saturday should contact Bradford Central police on (01274) 376459.