Usher stars in sex tape?

A sex tape allegedly featuring Usher and his ex-wife is up for sale.

The footage reportedly shows the 'OMG' hitmaker and Tameka Foster engaged in several X-rated acts, according to gossip website TMZ.

It is believed the recording of Usher and Tameka - with whom he has two sons, Usher V, three, and two-year-old Naviyd Eli - was among $1 million worth of items that were stolen from his car in December 2009.

It is not clear at which point during Usher and Tameka's relationship the video was made, though TMZ say they have seen the footage and some still images and confirmed it is the former couple.

Late in 2009, the R&B reported items including jewellery and two laptop computers had been taken from his vehicle.

A spokesperson for the singer has not yet commented on the sex tape reports.

Usher, 32, is not the first celebrity to become the unwilling star of a sex tape.

Former Playboy model Kendra Wilkinson was left "hurt" last year when a video she made with then-boyfriend Justin Frye when she was just 18 was released as a DVD entitled 'Kendra Exposed' last year.

Paris Hilton was seen participating in several sex acts with her ex-lover Rick Salomon in the DVD release '1 Night in Paris'.