Barry Lovejoy, head of the colleges department at Natfhe, was commenting after the Association of Colleges' latest pay survey and the publication of a new report from the Commons education select committee.
The AoC says it will not share the details of its research. But even its summary of the findings confirms most colleges are a long way from implementing the pay deal.
Natfhe estimates the deal would leave its members better-off by an average of 8 per cent - going a long way to narrowing the pay gap with schoolteachers.
But, according to the AoC's figures, only a quarter of colleges have said they have made, or intend to make, the changes to the lecturers' pay structure, which includes a 3 per cent across-the-board pay increase.
Mr Lovejoy said: "If the AoC has problems implementing the pay deal in full, it should own up and negotiate with the trades unions in an open manner.
"Some of its figures don't reflect what is happening on the ground.
"It has not shared the detailed findings with us and, instead, what has gone out is their spin on something which is a mess and a disgrace."
The select committee's recent report Public Expenditure on Education and Skills said better pay for lecturers would help make FE strong enough to cope with increased numbers of 14 to 16-year-olds in colleges.
It added: "It makes no sense that a student undertaking a course at a further education college should ... be less well funded than a student taking the same course at a school. The Secretary of State appears to recognise that truth, but progress towards equal funding is painfully slow."
The AoC refused to comment on Natfhe's criticisms but said it welcomes the select committee's comments.
Julian Gravatt, the AoC's director of funding and development, said: "The Government made a commitment in 2001 to close the gap, but we are still waiting for harmonisation. Lack of action means that the Government continues to short-change the majority of 16 to 19-year-olds."