The middle-aged English teacher was filmed taking off his shirt by students using a mobile phone.
He was ordered off the premises by headteacher David Forrest as footage of his antics circulated round the school.
A mobile phone video of the bearded teacher later finished up on the internet site You Tube.
A Suffolk County Council education spokesman said the man would not be teaching in Suffolk schools again.
The incident happened in front of a class of 13- and 14-year-olds.
Neither headteacher Mr Forrest nor education officials would confirm the name of the supply teacher involved, who was employed through a Hertfordshire-based agency.
A county council spokesman said: "As soon as the headteacher was made aware of the incident the supply teacher in question was asked to leave the school premises immediately.
"The matter was also reported immediately to the supply agency who employed him."
The spokesman confirmed the individual was no longer on the list of supply teachers available through the placement service regularly used by Suffolk County Council.
"In this instance, the individual was not contracted through that agency, he was contracted through an agency that had no connection with Suffolk County Council," he said.
Mr Forrest said the teacher was not one who had been regularly used by the upper school, which booked supply staff through a wide variety of agencies.
He said he had seen the video of the topless incident, soon after it happened two months ago and before it appeared on You Tube.
But he said he would not confirm the name of the teacher involved because disciplinary matters were private between the school, the man concerned and his employer.
barbara.eeles@sudburytoday.co.uk