The new term-time-only "assignments" - which affect a third of those on their books - were in response to the European Union's working time directive, which came into effect on October 1. This lays down that anyone in continuous employment for 13 weeks or more can accrue rights to paid annual leave.
But the move was condemned by lecturers' union, NATFHE, as "Dickensian". The union said:"The spirit of Scrooge is alive and well."
Richard Eve, ELS director of business strategy, defended the move, saying that 70 per cent of the lecturers affected had responded and nearly of all of them had accepted the new terms.
He said: "We are not taking anything away from anybody. We have reissued contracts to reflect the reality of what people teach. Where a lecturer works for 13 weeks or more of continuous lecturing their contract reflects that and they have an entitlement to paid holiday. But the vast majority work for 12 weeks or less."
But Paul Mackney, NATFHE general secretary, said he would be raising the matter with government ministers. "Last week, in response to the Select committee report on FE, the Goverment agreed that part-timers, whether employed by agencies or colleges should have fair treatment," he said. "It promised new rules governing the conduct of these agencies and they won't be a moment too soon."