Kristen Stewart has reportedly issued a public apology to her boyfriend and Twilight co-star Robert Pattinson following claims she had a brief affair.

The Snow White And The Huntsman actress was linked in US reports with the film's British director Rupert Sanders.

The 22-year-old American reportedly issued her apology to People magazine in the US.

It was quickly followed by an apology from 41-year-old Sanders to his family, also through People.

Stewart has been in a relationship with British actor Pattinson, 26, for some years. They met on the Twilight set in 2008.

Sanders is married to model and actress Liberty Ross, 33, with whom he has two children.

Ross portrayed the mother of Stewart's Snow White in the Huntsman tale.

Pattinson and Stewart were pictured together promoting the final Twilight film, Breaking Dawn - Part 2, at San Diego's Comic-Con earlier this month.

Stewart was reported to have said in a statement: 'I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected.'

'This momentary indiscretion has jeopardised the most important thing in my life, the person I love and respect the most, Rob.

'I love him, I love him, I'm so sorry.'

Sanders reportedly said in a statement that he is 'utterly distraught about the pain I have caused my family'.

He went on: 'My beautiful wife and heavenly children are all I have in this world. I love them with all my heart. I am praying that we can get through this together.'

Stewart and Pattinson play lovers in the Twilight series, which is set to conclude in November with the release of the final film.

Snow White And The Huntsman was released last month.