Roberts is to make her acting return in a Broadway play

Hollywood Reporter's annual Women in Entertainment Power list suggests she earns $20m (�11.6m) a film, despite her recent career break to have twins.

Nicole Kidman is second on $17m (�9.8m) per movie followed by Reese Witherspoon and Drew Barrymore on $15m (�8.7m).

Roberts, whose last film was Ocean's Twelve, will return to acting in 2006 making her Broadway stage debut.

She will appear next April alongside Paul Rudd, who played actress Lisa Kudrow's husband on TV's Friends, in a revival of Three Days of Rain.

The 1997 play written by Richard Greenberg features two interlocking stories taking place in different decades.

Box office attraction

Roberts became the first actress to join the likes of Tom Cruise in the ranks of the $20m-per-movie stars after scooping the best actress Oscar in 2001 for her role as the campaigning Erin Brockovich.

POWER LIST TOP 10 Julia Roberts Nicole Kidman Reese Witherspoon Drew Barrymore Renee Zellweger Angelina Jolie Cameron Diaz Jodie Foster Charlize Theron Jennifer Aniston

She picked up the People's Choice Award on nine occasions between 1991 and 2004 - an illustration of her enduring popularity with film-goers.

The 38-year-old, who is married to cameraman Danny Moder, gave birth last November to twins Phinnaeus and Hazel.