Image caption The current series of Sherlock has had an estimated 11m viewers per episode

The final episode of the current series of Sherlock has been leaked online.

A Russian version of the last instalment of series four - titled The Final Problem - has been illegally uploaded to the internet prior to it airing on television.

The creators of Sherlock have urged fans not to spoil the episode by sharing it online.

A post on the programme's official Twitter page said it was aware the episode had been uploaded illegally.

"If you come across it, please do not share it. #KeepMeSpoilerFree," it urged fans.

Sherlock producer Sue Vertue also tweeted: "Russian version of #Sherlock TFP has been illegally uploaded. Please don't share it. You've done so well keeping it spoiler free. Nearly there."

A preview screening of the series finale was held on Thursday in London for journalist and television critics.

Creator Steven Moffat has suggested another series of the detective drama "was possible" and he and fellow creator Mark Gatiss were not planning for the latest episode to be the final ever instalment.

Fans of the show will be able to watch The Final Problem at more than 300 cinemas as it is shown alongside its TV broadcast.

Audiences will have to pay for the cinema experience but will be treated to extra footage.

The series finale will air on BBC One at 21:00 on Sunday.