John Harwood, chief executive of the Learning and Skills Council, has defended his comments on a radio programme about "unacceptable" and "appalling" standards in further education.
But he apologised to the Association of Colleges about the way his criticisms were "distorted" by "severe editing" on the BBC's Today programme last weekend.
He has warned that college chiefs must face the fact that nearly half of provision is not up to scratch, and that about 5 per cent is "completely unacceptable".
His warning was backed by John Healey, the minister for adult skills, who said this week he thought that "standards vary far too widely".
Mr Harwood's comments were presented by the BBC alongside concerns raised by Ofsted chief inspector Mike Tomlinson as an attack on the quality of colleges.
In the Today report, Mr Harwood said: "We reckon about 40 per cent of the provision across the whole of the sector is just unacceptable in terms of the quality of the learning and the provision which takes place. And of that we think about 5 per cent of the sector is appalling."
In a letter to AoC chief executive David Gibson, Mr Harwood condemned the way his comments, taken from a long interview on the strengths and weaknesses of further education, were reduced to "a few seconds".
Mr Harwood told The THES that he stood by his view that while a lot of FE provision was world class, there was a high proportion that needed to be improved. "We need to start from the fact that it is not as good as it needs to be," he said.
A £160 million standards fund has been earmarked to tackle the problem.
Mr Gibson said the AoC was "shocked" that Mr Harwood had chosen to highlight weak provision rather than progress that had been made.