The Ministry of Justice has launched an investigation after convicted paedophile Rolf Harris entered the grounds of a Berkshire primary school.
The school's head teacher confronted the former TV star, who was in conversation with a local sculptor, and asked him to leave the site.
The MoJ said it was "looking into these reports and will take appropriate action".
Harris was jailed for five years in 2014 but released on licence in 2017.
A spokeswoman for the MoJ added: "When sex offenders are released they are subject to strict licence conditions and are liable to be returned to custody for breaching them."
Head teacher Richard Jarrett said: "In line with our standard procedures, an uninvited individual was asked to leave the outer perimeter of the school site yesterday, which he did without delay.
"At no time did any of our pupils come into contact with the individual nor was the individual invited by us onto the school grounds."
Harris was seen waving to children as they were waiting in the school hall for their lunch on Tuesday.
He was talking to sculptor Nick Garnett, who was working in the school's "Kiss and Drop" area.
Harris was seen waving to children as they were waiting for their lunch
Mr Garnett told the BBC: "I turned round and there was Rolf Harris, which was a strange moment.
"He asked for a piece of timber. Apparently he's interested in making some carvings, so I gave him a couple of pieces."
He said: "At no point was he near any children. The headmaster dealt with it incredibly calmly."
Speaking to the Press Association, the parent of a pupil at the school said: "What was he doing there?
"I feel like it was a really bad judgement call and I don't think his excuse is effective enough."
Thames Valley Police said: "A report was made that a man was on the site of the school.
"An officer attended the scene but no offence was committed. No arrests were made and advice has been given to the man involved."
Australian-born TV presenter Harris was jailed in 2014 for 12 indecent assaults, relating to four girls between 1968 and 1986.
In May 2017 he was cleared of four unconnected historical sex offences, which he had denied.
In November 2017 one of the 12 indecent assault convictions was overturned by the Court of Appeal.