Lee Mack is joining 'Line of Duty' for a Sport Relief skit.

Lee Mack

Lee Mack

The hugely popular crime drama is back later this year for season six, but fans will get a unique look at the BBC One show when the comedian joins the cast for a hilarious one-off sketch during the charity telethon on March 13.

The skit will see DS Steve Arnott (Martin Compston), DI Kate Fleming (Vicky McClure) and Supt. Ted Hastings (Adrian Dunbar) grilling crooked cop DC Taylor - played by Jason Isaacs - about the identity of the real 'H'.

In a funny twist, his legal representation comes in the form of hapless lawyer David Rickman, who is played by the 'Not Going Out' star.

Another BBC drama will be getting a Sport Relief twist next month, with 'Killing Eve' becoming 'Killing Steves' as a blonde assassin takes out victims all with the same first name.

Her targets are set to include snooker legend Steve Davis, Olympic rower Sir Steve Redgrave, 'Saturday Night Takeaway' star Stephen Mulhern and 'Coronation Street' actor Steve McDonald.

Meanwhile, filming is already underway for the upcoming sixth series of 'Line of Duty', with the team back to work on the upcoming run.

In a behind-the-scenes snap, Adrian Dunbar and Martin Compston can be seen on set as Superintendent Ted Hastings and Detective Sergeant Steve Arnott respectively.

They will be joined once again by fellow series lead Vicky McClure, who returns in the role of Detective Inspector Kate Fleming.

The new season - which is set 18 months on from the fifth series - will centre on a new case for AC-12, with Kelly Macdonald joining the cast as new, enigmatic Detective Chief Inspector Joanne Davidson.

Also confirmed for the upcoming run are Shalom Brune-Franklin, Perry Fitzpatrick, Andi Osho, and Prasanna Puwanarajah.

Jed Mercurio returns as writer for the sixth series, and Gareth Bryn, Daniel Nattheim and Jennie Darnell will direct, with Ken Horn returning as a producer.