Police raided Sir Cliff Richard's home in Berkshire, last August
An historical sex offence inquiry into Sir Cliff Richard has "increased significantly in size", South Yorkshire Police has said.
The expansion of the investigation meant no date could be given for when it would be concluded, South Yorkshire Police's chief constable said.
It comes after police raided Sir Cliff's Berkshire home last August.
He was interviewed about a claim of a sex crime involving a young boy, but was not arrested or charged.