Mariska Hargitay teases Christopher Meloni's return to Law & Order: SVU

Mariska Hargitay has confirmed Christopher Meloni will appear in an upcoming episode of Law & Order: Special Victims Unit.

On Tuesday, the actress - who plays Olivia Benson on the crime drama - took to her Instagram account to share a photo of herself and her longtime co-star, who was facing away from the camera.

"Who dat?" she wrote in the caption.

A few hours later, Mariska posted a selfie of herself and Christopher, who portrayed Elliot Stable, beaming.

"Happy 600..." the 62-year-old exclaimed, indicating the actor will feature in the 600th episode of season 28.

The forthcoming season is set to premiere on 29 September.

Representatives for NBC have not yet commented on the news.

Christopher was part of the main cast for the first 12 seasons but has made guest appearances on the show since and reprised the role in the spin-off, Law & Order: Organized Crime.

And in an interview for Variety published in April, the Oz star recalled how he and Mariska had an instant connection.

"The key of it was humour. If you can communicate through humour, then you have a very tight bond. You experiment with how far you can go," the 65-year-old explained. "Sometimes it can be very cutting. Sometimes it can be very close to the bone of truth. And if each person can withstand the shots - we may play rough with each other, but if we can communicate comfortably, we can figure out the other stuff." 

Mariska has played Olivia since 1999, making the protagonist the longest-running character of all time in an American primetime drama.