Fans just cannot wait for BBC's hit series "Sherlock" to return to television but it now seems their patience could be tested again as season 4 of the detective drama is facing further delay.

It is now understood that the production of "Sherlock" season 4 has not yet begun and, contrary to recent reports, the details for the brand new season are still being worked out.

"We're literally in the middle of working out what we're doing and the dates we've got. It's a bit of a watch-this-space, I'm afraid," Sue Vertue, executive producer of "Sherlock", told Vulture.

It was previously reported that the principal reason for "Sherlock" season 4's delay is Benedict Cumberbatch and Martin Freeman's busy schedules. The two actors are apparently busy with other projects as they are in much demand, post the insane popularity of "Sherlock".

While season 4 is still in the making, all three episodes of "Sherlock" season 3 have been released through Netflix Watch Instantly. The episodes include "The Empty Hearse", "The Sign of Three" and "His Last Vow".

Besides the season 3 episodes, a special feature called "Sherlock Uncovered" has also been released. The special revolves around a few specific aspects of the popular British series and is shot in three parts.

The first special, called "Sherlock Uncovered: The Return", showcases the return of the cast for season 3. The cast and crew is shown attending the table reading of the first episode.

The second in the specials series is "Sherlock Uncovered: The Women", which throws light on the women in Sherlock Holmes' life, both on the show as well as in the books. The cast and crew examine Sherlock's relationship with various women as the camera captures them.

The last and final special is named "Sherlock Uncovered: The Villains", and as the name goes, it focuses on the villians Sherlock has come across till date.

The exclusive Sherlock content is available through Netflix. And now that season 3 has been put up for online streaming, the entire collection of Sherlock is available to stream on Netflix.