Doctor Who fans rejoice — the BBC says it has recovered nine episodes of the sci-fi series that were feared lost in space and time.

The broadcaster says the missing episodes, and two others, were found in the storeroom of a television relay station in Nigeria.

Doctor Who was first broadcast in 1963 and remains one of the BBC's most popular programs. Some early episodes were lost because the broadcaster wiped the tapes clean for re-use.

The BBC says the lost episodes were tracked down by tracing records of overseas shipments of BBC tapes for transmission. The recovered episodes date from 1967 and 1968 and feature Patrick Troughton, the second of a dozen actors to play the show's time-travelling alien hero.

They consist of most of two six-part stories: The Web of Fear and The Enemy of the World. They will be offered for sale on iTunes from Friday, and later on DVD.

Almost 100 episodes of the series are still missing.

Doctor Who celebrates its 50th anniversary this year. In August, the BBC revealed that British actor Peter Capaldi would step in as the next star of the long-running science fiction series, replacing Matt Smith, who became the 11th and youngest Doctor when he took on the role at age 26 in 2009.