It is understood the duo are set to record a show together later this year at the newly re-opened Television Centre studios. However, all other details about the project are currently being kept under wraps.
The "top secret" special is still in development and exact details have yet to be confirmed. It is likely to be broadcast at Christmas.
The comedy duo's French And Saunders sketch show began on the BBC in 1987 and ran on-and-off until 2007, with the last series titled A Bucket O' French And Saunders. A new special is likely to mark the programme's 30th anniversary.
French & Saunders last appeared on stage together in June to pick up an Aardman Slapstick Comedy Legend Award (pictured above); meanwhile their most recent comedy performance together was in March, when they spoofed Carpool Karaoke as part of the Comic Relief live TV broadcast.
Referring to the new special, a BBC spokesperson told British Comedy Guide that "more details will be revealed in due course".
A DVD box set containing the complete six French And Saunders series to date - although not their much-loved specials - is available to buy.
Sunday 17th September update
Speaking to The Sunday Times, Dawn French revealed of the special: "There's some Handmaid's Tale in there - we had fun with some of those costumes."
The programme will also spoof reality TV shows like The Only Way Is Essex and Love Island.
French said of the contestants: "I am shocked by how they behave. These girls are preloading with vodka, primping, helping each other get ready. You reckon they want to meet someone who would love, cherish and respect them. But instead they go out and get utterly hammered and are shagging in a bush and coming out and going 'Yes!', like men. Like the men we hoped we wouldn't ever be like, and certainly not mimic as women - being champions of the shag machine and going home covered in sperm on their legs, and throwing up.
"I don't believe that you feel great about yourself the day after that. I don't think boys do particularly either. Is that what women threw themselves in front of horses for? For this? For girls to be as low as those awful boys. What have we done? How did we go wrong? They have mothers who love them. What's happened that they don't value their body or that they don't mind any of this? Am I totally out of step? Is it really OK to be as sexually free as you like and as drunk as you like? I don't buy it. It feels wrong to me."