The claims have emerged as police investigate a range of historic allegations of football-related child abuse across Scotland.
King, known as Gerry, was suspended after his arrest in February.
Yesterday, he strongly denied the allegations and said he was challenging them. He said: “It has completely destroyed me. You work 42 years and then this happens.”
King also confirmed that he is a former chairman of Celtic Boys Club, which has been rocked by historic sex abuse scandals.
But he insisted the police investigation was not related to his years there and said he not been chairman of the club for around eight years.
He insisted: “It’s got nothing to do with the boys’ club at all. It’s the school.”
King has taught a number of subjects at St Martha’s in Balornock, Glasgow. But he said the allegations against him, which date back three decades, were linked specifically to sport.
He said: “They’re 30 years ago. You’ve got things in place so it couldn’t happen and they’ve said it did. I have been advised by the lawyer not to say anything.”
He said of the police investigation: “It’s hellish, it’s terrible. They said it can take anything up to nine months away into next year.”
King was at Celtic Boys Club with Jim Torbett, who got two years’ jail in 1998 for abusing three former players, including future Scotland striker Alan Brazil, between 1967 and 1974.
Torbett was said to have been sacked from the club in 1974 when allegations surfaced against him. But this week, fresh claims were made that he abused more youngsters after returning to Celtic Boys Club for a spell in the 1980s and 90s. He denies the new allegations.
King also worked at Torbett’s company, the Trophy Centre, but denies being close to him.
He said: “Everybody has got different teams. I worked there for about a year but only on a Saturday afternoon.”
About his time as chairman of the boys’ club, he said: “That was about eight years ago. We left that to the younger ones – we did our stint.”
King’s association with Celtic Boys Club dates back to the early 1980s. In 1982-83, he helped run the under-12 team which won an invitational event in Rotterdam, Holland.
In the summer of 1983, King joined senior players from the boys’ club on a trip to Kearney, New Jersey, USA. He wrote a Celtic View article on the visit, headlined Trip of a Lifetime.
King took charge of the under-14s the following season but returned to the under-12s in 1984-85 and helped them win the Scottish Juvenile Cup.
He coached teams at St Martha’s for decades and a number of his players went on to professional careers.
A source said: “A lot of people will be really shocked by this – he was very well known. A number of high-profile players that he coached over the years have been interviewed by police.”
Police confirmed: “On February 15, 2017, a 65-year-old man was charged in connection with non-recent sexual offences. A report has been sent to the Procurator fiscal.”
Glasgow City Council said: “A member of staff was placed on precautionary suspension in February pending a police investigation.”
A spokesman for Celtic Football Club said they had no comment to make about King and referred our reporter to an earlier statement they gave about historic abuse.
It said Celtic Boys’ Club was a “separate and distinct” organisation from Celtic FC, but asked anyone with concerns to contact them.
The statement added: “A large number of football clubs across Britain have been impacted by these historical issues. Celtic Football Club considers it of the utmost importance that football, other sports organisations and all areas of society ensure that the issue of safeguarding is given the attention it deserves.”
Celtic Boys’ Club were unavailable for comment last night.