"Twilight" star Kristen Stewart has issued an apology after admitting that she had an illicit affair with the director of her latest movie.

American Stewart, 22, the most bankable actress in Hollywood, confessed via People magazine that she had cheated on longtime British boyfriend and "Twilight" co-star Robert Pattinson, 26.

"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected," said Stewart, whose new film "Snow White and the Huntsman" hit US theaters in June.

"This momentary indiscretion has jeopardized 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."

Pattinson has so far maintained a public silence on the affair.

"Snow White" director Rupert Sanders made his own statement, saying he was "utterly distraught about the pain I have caused" to his wife of seven years, model Liberty Ross, 33, and their two young children.

"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," said Sanders, who, like Pattinson, is English.

Prompting both apologies was Us magazine, which revealed Tuesday it would be running "exclusive photos" of Stewart and Sanders "packing on the PDA" (the acronym stands for "public displays of affection") in its next issue.

It said the photos were snapped in Los Angeles on July 17.

People magazine said Stewart and Pattinson have been increasingly open about their four-year relationship, while E! Online quoted a source as saying the Stewart-Sanders fling occurred after the filming of "Snow White" was finished.

The second half of "The Twilight Saga: Breaking Dawn" is scheduled to hit theaters in November, after part one helped Stewart earn $34.5 million in the year to May, more than any other Hollywood actress, according to a Forbes list.