Michelle Williams has expressed her disappointment after an unfinished song featuring Beyoncé and Kelly Rowland leaked online.

The singer has teamed up with her Destiny's Child bandmates for the new track 'Say Yes', which is expected to feature on her upcoming solo album.

A version of the tune emerged online recently, but Williams took to Twitter to confirm that it hasn't properly been mixed or mastered yet.

She wrote: "Unfortunately an unmixed and mastered version of a song was leaked today! Wanted it 2 be presented right! Thx for the love though! #pissed.

"I still need the support when it's officially released! Okay? Help your girl reach #1........it's about time right? LOL!!!"

The three Destiny's Child bandmates reunited in 2013 to perform at the Super Bowl half-time show.

They were also pictured this week (May 20) filming a video together in Maplewood, New Jersey.

Listen to the unfinished 'Say Yes' below: