Kristen Stewart apologises for cheating on Twilight co-star Robert Pattinson

Robert Pattinson, left, and Kristen Stewart pictured at the UK premiere of Breaking Dawn in November 2011. Credit: PA

Actress Kristen Stewart has issued a public apology for cheating on boyfriend and Twilight co-star Robert Pattinson.

Reports across the pond claimed that Stewart, 22, had a short affair with Rupert Sanders, who was her director in 2012's Snow White and the Huntsman.

To complicate matters further, Liberty Ross, Sanders' wife, also appeared in the same film.

It's not known for how long London-born heartthrob Pattinson, 26, has been dating Stewart, but the duo first appeared together in the first film of the Twilight saga in 2008.

In Stewart's apology, published today, she appeared to refer to a fling with Sanders as a "momentary indiscretion".

Celebrity gossip website PerezHilton.com later published a statement from Rupert Sanders, who apologised to his family for the "pain" he says he has caused:

The Twilight stars both recently made it into a list of the top 10 highest-paid celebrities under the age of 30, with Stewart and Pattinson estimated to have earned £22m and £17m respectively.