Kelly Osbourne is working on a ''secret project'' with her mother Sharon Osbourne.

The 'Fashion Police' co-host, who is getting ready to marry her vegetarian chef boyfriend Matthew Mosshart, revealed the duo are preparing to unveil a mysterious new venture, which they have been working on for a decade.

The 28-year-old star tweeted on Friday (04.10.13): ''My mum & I have been working on a project together for over 10 years today is the day it is finally happening! Cant wait 4 you guys to see!! (sic)''

She later hinted that the project involves fashion as she tweeted the message: ''I can't wait for you guys to see what all this primping #DivaStyle is for!!!! I'm in #DragQueenHeaven!'' along with a picture of herself being groomed by her makeup and hair stylists.

Kelly later admitted she was exhausted after a long day of working alongside her mother, 60, who is currently flying transatlantic several times a week to appear on the 'X Factor' in London and film her chat show 'The Talk' in Los Angeles.

She tweeted on Saturday morning (05.10.13): ''My mum & I just worked a 24 hour day I'm so tired I feel like s**t but it was so fun I feel like a d**k for complaining!''

They also have another big project in the works as they've joined forces to plan Kelly's upcoming wedding.

Sharon recently revealed that she is planning her daughter's nuptials, which will take place at their home in Buckinghamshire, England.

She said: ''It's going to be very English and very Victorian. At our house in England.''