Vladimir Bukovsky, the veteran Soviet era dissident, said downloading more than 20,000 indecent images of children was a hobby "like stamp collecting", a court heard.

Bukovsky, 73, who sat in court in a wheelchair, is on trial accused of having accessed still and video images over 15 years, some of which were being downloaded at the point of his arrest in 2014.

He told police he had become curious at the end of the 1990s about issues involving control of, and censorship of the Internet and decided to look into what was available online, prosecutor Will Carter said.

The pensioner, who was living alone in Cambridge when he was arrested, said it had become something of a hobby, which he told no-one else about.

Mr Carter said: "What he said was that his initial curiosity turned into a hobby rather like stamp-collecting."

Bukovsky denies five counts of making indecent images of children, five of possessing indecent images of children and one of possessing a prohibited image of a child.