Russian broadcaster Channel One has blamed a mistake by an employee for the online leak of the Sherlock series four finale.
The broadcaster has said it has concluded its investigation into the leak of the episode, and found an error by en employee was to blame. It also promised that it wouldn't happen again.
A statement from the broadcaster said: "Channel One has concluded its investigation into the online leaking of the final episode of series 4 of Sherlock. We regret to confirm, that one of our employees non-maliciously broke our strict security protocols.
“As a result of this gross dereliction of duty, the file leaked online. We would like to reassure our partners and viewers that as a result of this incident, we have completely revised our content security procedures to ensure that this does not happen again, and we apologise to Hartswood Films, BBC Worldwide and Sherlock fans everywhere who have been impacted by this leak."
BBC Worldwide issued a statement which suggested it was happy with the outcome of the investigation: "Further to Channel One's findings that this was an isolated non-intentional content security lapse on the part of an employee, BBC Worldwide welcomes their reassurances that they will be tightening security procedures to eliminate any similar future risks and we will work closely with them to ensure this happens.
"We would like to thank the Sherlock fans who rallied together and helped us limit the episode’s leak last weekend. BBC Worldwide also appreciates Channel One's efforts in concluding their investigation so expediently and we now consider the matter closed.”
On Monday, Channel One, which holds the rights to air Sherlock in Russia, suggested that it may have been hacked “by an external third party” and promised an inquiry.
The move came after a Russian-language version of Sherlock series four episode three, The Final Problem, appeared online on Saturday, featuring a three-second continuity announcement identifying it as having originated from Channel One.
There had been speculation that the leak may have been politically motivated as a possible retaliation to the expansion of the BBC World Service’s Russian language output, and also against what are felt by some in Russia as punitive measures taken against the country's English language broadcaster RT by British regulators and banks.
A BBC source said this afternoon: "It wasn't Putin it seems".