A former Dragons' Den star who acted as an adviser to Prime Minister David Cameron has denied paying a 13-year-old girl for sex after meeting her on a "Sugar Daddy" website.

Doug Richard, 57, is accused of spanking the girl's bottom and engaging in other sexual activity after she travelled to London to meet him.

He appeared before the Old Bailey accused of three counts of sexual activity with a child, one of causing or inciting a child to engage in sexual activity and a charge of paying a child for sexual services.

All the charges relate to one girl who was aged 13 at the time of the alleged offences on January 2.

The US-born businessman, who is on unconditional bail, entered not guilty pleas during a short hearing before the Common Serjeant of London, Judge Richard Marks QC.

Dressed smartly in a dark suit, he spoke clearly in a thick American accent.

Richard, of Islington, north London, is due back at the same court for a five-day trial starting on January 25. A further hearing before trial judge Mark Lucraft QC was scheduled for January 8.

The millionaire, who appeared on BBC's Dragons' Den in the first two series, reportedly travelled with the Prime Minister on an official government trip to Africa and advised on policy.

His association with Mr Cameron goes back to at least 2008, when the then opposition leader invited the technology entrepreneur to write a report about small business in Britain.

He founded a business loans initiative called School For Startups, alongside the Department for Business, Innovation and Skills.