British singer Cliff Richard has pulled out of a ceremony where he was to be awarded the Keys of the City of Albufeira near his holiday home in Portugal.

The millionaire pop star, who is facing an historical sex assault allegation, was to receive the region's top civic honour on Wednesday.

A dozen others were given medals of merit during a day of celebrations to mark the granting of an ancient charter.

Mr Richard told officials he would not be there and stayed in his villa in the hills above the Algarve resort where he has had a summer home for more than 50 years.

Mayor Carlos Silva e Sousa said "Cliff was to receive the gold Key of the City because he is a distinguished member of Albufeira. He is not here today because it is his choice, but we have kept the invitation and hope to give him his award some time."

The city's full council voted in secret and unanimously to make the award two weeks ago. The mayor said the singer had planned to attend the ceremony but sent a message recently to say he had to decline the invitation.

Mr Silva e Sousa added that he was aware of the police investigation into an allegation that Mr Richard had sexually assaulted a young boy at an evangelical rally in Sheffield in 1985.

He said "I don't know why he is not here. It doesn't change my opinion of him. We are very proud of him. He is a big man."

Officials said they had agreed with Mr Richard's decision because his presence would have overshadowed the ceremony.

The medals of merit were awarded to three individuals - one posthumously - and nine organisations who were said to have promoted Albufeira around the world.

Sir Cliff bought his first villa here in 1961 in a resort that has become popular with British holidaymakers.

Twenty years ago he bought a bigger home and planted a vineyard on a plot near a bigger estate where he makes his own wine in partnership with a friend.

He spends several weeks at his Portugal home each summer, usually arriving after visiting the Wimbledon tennis championships and staying until September.

He has rarely been glimpsed on the 30-acre estate since police raided his UK home in Berkshire last week.

Mr Richard has also pulled out of a performance at Canterbury Cathedral in September and apologised for the disappointment and inconvenience.

He has described the sex allegation as "completely false" and said he would co-operate with the police investigation. Detectives said they want to speak to him and are expected to interview him in the next few weeks.