BBC One has confirmed that Sherlock will return next year with a special, followed by its three-episode fourth season.

“A special, plus a new series of three episodes -- it's a record-breaking run!" co-creator Steven Moffat said in a statement. "Of course, it's far too early to say what's coming, but we're reasonably confident that the very next thing to happen to Sherlock and John, is the very last thing you'd expect ...”

Martin Freeman had let the word slip about the special, telling The Telegraph that he and co-star Benedict Cumberbatch would reunite early next year to shoot a 2015 Christmas special. According to BBC One, the special will film in January, with the fourth season shooting later in the year.

The TV channel's Twitter feed account today teased the new season as "the most shocking and surprising" one yet, and posted an image of Andrew Scott as Moriarty with the words "Miss me?"

"After the briefest of exiles, #Sherlock will return to face one of his biggest mysteries yet ... why is Moriarty’s face being broadcast on every television in the land?"