A number of early episodes of Doctor Who, which were believed to have been permanently lost, have been returned to the BBC.

BBC Worldwide is expected to confirm the find at a press screening in London later this week.

It follows weeks of speculation that some lost episodes had been located.

A total of 106 episodes featuring the first two actors to play the Doctor, William Hartnell and Patrick Troughton, are currently missing.

The BBC destroyed many of the sci-fi drama's original transmission tapes in the 1960s and 1970s.

However, the majority of the episodes had been transferred on to film for foreign broadcasters. It is often these prints found in other countries that are the source of retrieved episodes.

BBC to reveal a number of missing Doctor Who episodes