Geoff Lennox, chief executive of Education Lecturing Services, says NATFHE is out to get the company through a campaign of vilification. But the union insists it is only stating its case based on evidence.

The agency was set up earlier this year to offer colleges greater flexibility on the employment of part-time staff. Many colleges then fired staff or refused to renew contracts directing them instead to register with ELS.

Complaints are being logged daily by NATFHEconcerning ELS, which claims to have 45,000 freelance lecturing staff on its books five months after its launch. Officials are compiling a dossier of case histories with a view to bringing tribunal cases against ELS. The TES has also received 12 complaints from non-NATFHE lecturers.

Liberal Democrat education spokesman Don Foster weighed in to the debate, claiming ELS conducted itself “like a double glazing firm rather than an educational service” and pledged to raise the issue in Parliament.

ELS has denied suggestions of fundamental problems and accused NATFHE of scurrilous tactics to discredit its operations, including putting lecturers up to complain about their treatment.

Principals will admit to some early difficulties, but insist they will soon be resolved a stance that may do little to smooth over bitter resentments among staff who believe their livelihoods are in the balance in a shaky system.

NATFHEnegotiating secretary Sue Berryman said callers frequently listed a common set of grievances, including:

* Being offered work for which they were totally unsuited or at a level they did not request. One lecturer claimed to have been asked to teach special needs students when he had no experience in that area;

* Rates of pay varying by as much as 25 per cent to teach the same class in different colleges and between Pounds 1-Pounds 2 an hour less than the rates offered before staff became sefl-employed. Callers claim the colleges brush their complaints aside, saying they are no longer their responsibility;

* Assignments offered after the starting date of classes or often at very short notice, such as the night before the course is due to start;

* Unsolicited mailshots arriving from ELS when staff had not given permission to any agency to release their details to such organisations. All suspected that college administrators had passed on details without permission. The cases are being investigated by the Data Protection Agency.

For many lecturers, underlying resentment also stems from the belief that colleges switched to ELS primarily to avoid new obligations to treat part-timers on the same basis as their full-time counterparts following a House of Lords ruling in March.

But with 108 out of 350 colleges now signed up to ELS, the new system is undeniably up and running and the issue for students and colleges now is quality of the education offered.

NATFHE representatives on the ground, suspicious of the agency from the outset, believe their fears over standards have been more than confirmed.

Alan Lauder, NATFHE branch secretary at North Tyneside College, reported some classes without any teachers at all for the first few weeks and other classes where the teachers were unprepared because they had been recruited at such short notice.

Lawrence Toye, principal of North Tyneside, said it was normal to have disarray at the beginning of the academic year because of the vagaries of enrolment.

“In fact we’ve had less disruption this year than in the past. I have no complaints about ELS.”

Jeannette Nelson, a modern languages lecturer at Oaklands College, Hertfordshire, and chair of NATFHE’s further education industrial relations committee, said courses were starting without the usual planning because no one knew who the part-time lecturers would be.

But Geoff Lennox, chief executive of ELS, rejected most of the allegations. “I am not saying there might not have been mistakes,” he said. “But we have had a lot of scurrilous action by NATFHE fictitious applications, getting individuals to complain, telling people that their fees should be higher, and so on. ”

Part-timers with grievances should contact him, he said, and he would investigate. He promised no discrimination against complainants.

The union, however, dismisses these allegations. “Given the huge number of problems in the sector,I don’t think we have to go manufacturing them,” said Ms Berryman.

Some college principals say there have been “teething problems” caused by the switch to ELS. Keith Gardner, principal of Oaklands, said there had been one or two examples of a mismatch between a lecturer and a course. These were resolved immediately, he said.

He added: “We’re feeling our way and there have been some difficulties in a new set-up.”

Both men said that some lecturers would find differences in their pay, but Mr Lennox emphasised that ELS was not paying badly. Its current average was Pounds 17.24 an hour compared with a national average of Pounds 14.57 previously.

The agency’s own figures, meanwhile depict a flourishing operation. Mr Lennox says turnover was more than Pounds 10m in the first month of operation.