Sir Cliff Richard, facing a historical sexual assault claim, has withdrawn from a charity event because he did not "want the event to be overshadowed by the false allegation", his spokesman said on Tuesday.

The singer was due to perform at Canterbury cathedral on 26 September in a fundraising concert. The statement added: "He is sorry for any disappointment or inconvenience caused."

Police searched Richard's apartment last week as part of an investigation into an alleged sexual assault on a young boy at a religious event in 1985 in Sheffield. The pop star, who was in Portugal at the time of the search, has denied any wrongdoing.

The decision to pull out of the event for the Canterbury Cathedral Trust comes after the pop star, 73, hired the high-profile lawyer, Ian Burton.

Celebrities have jumped to defend Richard, saying the allegation was "completely false". Cilla Black said: "I, like everyone else, was very shocked to hear of these allegations and I am absolutely positive that they are without foundation."

The BBC's live coverage of the search of Richard's £3.5m Berkshire residence has led to allegations of a witch hunt and prompted a parliamentary inquiry.

The BBC director general and South Yorkshire police were told on Monday that they would be called to give evidence to MPs over the handling of the child abuse investigation.

Keith Vaz, the Commons home affairs committee chairman, said he was "concerned by the methods or process" that the BBC used in its live broadcast of the police search.

The concert was part of a series of events being held by the cathedral, which dates back to the sixth century, next month to mark the charity's 40th anniversary. Richard has been a poster boy for the Christian faith and once told the Church of England Newspaper: "If I lost my career, I don't think God would dump me."

Canterbury Cathedral representatives were not available for comment on Tuesday night.

• This article was amended on 20 August 2014. The Canterbury Cathedral Trust charity is celebrating its 40th anniversary, not the cathedral itself.