Phantom of the Opera star Emmy Rossum and Lindsay Lohan joined Kelly at the celebrity bash

A friend said: "After much soul-searching, Kelly decided that Billy is not the man she wants to marry and has called off the engagement.

"The split is completely amicable and the decision was made after long conversations here and in the US. They remain good friends."

Her marriage rethink is said to come after the death of her father, Kenneth Parsons, last November. Mr Parsons, 57, died following a battle with cancer.

Following her split from the Titanic actor, Kelly has reportedly been in touch with ex-boyfriend Jason Statham, who she dated for seven years before leaving him for Billy.

A friend of Kelly's told the Mail on Sunday, "Kelly and her family kept in touch with Jason when they split.

"Jason took ages to get over her and didn't date anyone for years.

"He's seeing someone now but is in touch with Kelly all the time. They are very good friends."