The Tory MP Michael Fabricant has apologised for suggesting many teachers and nurses enjoyed a “quiet drink” at the end of the day in staff rooms during lockdown.

In a letter published on the National Association of Head Teachers (NAHT) union’s website after outrage from the education sector over his comments, Fabricant said it was not his intention to cause offence or to demoralise, “and I apologise if I have genuinely done so”.

He added: “I applaud the work of nurses, GPs and others in the medical and teaching professions who worked long hours under difficult, and sometimes impossible, conditions during the height of the Covid pandemic to keep us all safe and to educate our children.”

He said in an interview with the BBC that he had explained he was neither “judging nor chastising the minority of nurses or teachers who chose to unwind with a few work colleagues after a long shift”.

He added: “Nor did I suggest that any were drunk.”

During the interview, the Lichfield MP said he did not think Boris Johnson knew he was breaking the law when he attended a gathering in Downing Street in June 2020 to celebrate his 56th birthday.

Johnson has subsequently paid a fixed-penalty notice for attending the event in violation of coronavirus rules.

Fabricant said: “I don’t think at any time he thought he was breaking the law … he thought just like many teachers and nurses who after a very long shift would go back to the staff room and have a quiet drink.”

In his apology, Fabricant said that since the interview, a number of other cases of teachers drinking at school had been brought to his attention.

He added this was “not surprising given that there are some 500,000 nurses and 625,000 teachers throughout Britain”, and he acknowledged the number of after-work drinks remained among a “small minority”.

He said: “My error in one part of the programme – which was repeated on TV – was to give the impression this was general practice by nurses and teachers: this was never the case.”

In his letter to the NAHT general secretary, Paul Whiteman, he said he felt that “if people were working closely together during the day and then met alone, without outsiders being present, they would be unlikely to spread infection”.

He added: “In the small number of cases where people did have a quick drink with close work colleagues, I both understand and sympathise with people who had endured a long and exhausting day. We are all human.”

He called for more “tolerance” for everyone who had been in a stressful work environment during lockdown and had met with colleagues afterwards.

Whiteman said: “We are pleased that Mr Fabricant has expressed regret for the effect of his comments – they were unjustified, unhelpful and damaging.

“While we appreciate his explanation, we must reiterate that we do not recognise the picture Mr Fabricant painted of teachers drinking together during lockdown. Education professionals worked tirelessly throughout the pandemic to keep pupils safe, supported and learning under exceptionally difficult circumstances.”

At its annual conference in Telford, Shropshire, this weekend, the NAHT will discuss condemning Fabricant’s comments and applauding the “swift public intervention” of Whiteman, who wrote to the education secretary, Nadhim Zahawi, to criticise the “wholly inaccurate and deeply insulting” remarks.

A conference motion says: “The subsequent apology issued by Mr Fabricant in response is welcome but we note that the slur has not been withdrawn. All too often we see baseless slurs and allegations made about the profession in an attempt to direct attention away from political failure.”

It calls on the union to “publicly correct false impressions without fear or favour at every opportunity”.