FILE - In this Tuesday, May 13, 2014 file photo, British singer Cliff Richard performs on stage during the first show of his European tour 'Still Reelin' And A-Rockin' at the o2-Arena in Hamburg, Germany. British police say they are searching a house belonging to singer Cliff Richard in connection with sexual allegations dating back to the 1980s. South Yorkshire Police say eight officers are at the house in Berkshire, west of London on Thursday, Aug. 14, 2014. The force said the allegations "involve a boy who was under the age of 16 at the time." (AP Photo/dpa, Markus Scholz, File)

London - Sir Cliff Richard is said to be angry at how long police are taking to investigate child abuse allegations made against him.

The 73-year-old star has strongly denied claims he sexually assaulted a young boy at an event in 1985, and he and his team will reportedly demand an explanation as to why the investigation has dragged on "for so long".

A source told the Sunday Mirror newspaper: "Sir Cliff and his team want explanations as to why the investigation has gone on for so long and why they burst into his home without warning."

The 'Summer Holiday' hitmaker is said to be keen to clear his name over the allegations, and he has felt "publicly humiliated" by the claims and the recent police raid on his home last week.

The insider added: "Sir Cliff feels publicly humiliated by the events of the past few days and is determined that this will not be repeated when he comes back to face the music.

"He wants to retain a sense of dignity in this whole very distressing situation."

Meanwhile, it was reported at the weekend that the singer may be forced to miss his annual trip to the US Open Tennis if refused entry into the country while police investigate allegations that he sexually assaulted a young boy at an event in 1985.

An insider told The Sun newspaper: “You would be mad to try to get on a plane if you had a child abuse inquiry hanging over you.”

However, people who have been questioned under caution by police can apply to the US Embassy for special consideration for a visa and will be assessed on an individual basis.

The US Embassy in London said: “We do not comment on individuals.”

It has also been reported he enjoyed a game of tennis on Saturday night as he tried to relax with friends. - BANG Showbiz