Sir Cliff Richard's Berkshire property searched by police
Police spokesman Det Supt Matt Fenwick said the allegation involved a boy under 16 and dated from the 1980s in the South Yorkshire area.
The search is being carried out by South Yorkshire Police and is not connected to Operation Yewtree.
Police said officers from that operation - set up by the Metropolitan Police to investigate hundreds of allegations in the wake of the Jimmy Savile scandal - had been notified.
Thames Valley Police said it had assisted the South Yorkshire force with the execution of a search warrant at the property.
The BBC's Dan Johnson said it had not yet been possible to get a response from Sir Cliff or his representatives.
He has sold 21.5 million singles - more than any other male British artist - and is the only performer to have had at least one UK top five album in each of the last seven decades.
He has represented the UK in the Eurovision song contest twice and in 2013 released the 100th album of his career.
He was knighted in 1995 and performed at the Queen's Diamond Jubilee concert at Buckingham Palace in 2012.