Kristen Stewart has been spotted wearing jeans to a friend's wedding.

The Twilight star, who is known for being a fashion rebel, forgot her dress so borrowed a Zac Posen cocktail number from the groom's sister for the ceremony, reported.

She later changed into jeans and a black blazer to party with fellow guests, while her boyfriend Robert Pattinson had a go at the DJ decks at the wedding, for Hollywood producer Kevin Turen and his new wife Evelina Oboza.

"They stuck to each other's side all night," a guest told the US magazine.

Zac Efron, Andrew Garfield and Will Kopelman were also seen at the wedding, which took place in Englewood, New Jersey.

Both Kristen and Robert will reprise their roles as Bella Swan and vampire Edward Cullen in the final part of the Twilight Saga, Breaking Dawn: Part 2 later this year.