(Cover) - EN Showbiz - Katherine Heigl's theatre etiquette was called into question during a recent New York outing, sources claim.

The 32-year-old Hollywood actress attended a performance of religious satire The Book of Mormon on Saturday night with mom Nancy, and was later joined by her musician husband Josh Kelley, 31.

Spies at the event have claimed the movie star's behaviour was rather diva-like, with reports in the New York Post that she "wore big dark sunglasses and discreetly bent down and puffed on an electronic cigarette during the show".

Katherine's other unusual conduct included arriving at the show 20 minutes after it had begun, meaning guests in the same row had to get up for her and Nancy. Josh was even later, arriving 10 minutes after his wife and causing theatregoers to move again so he could sit with her.

The Book of Mormon mocks organised religion and the traditional format of musical theatre, and has been receiving rave reviews.

A representative for the actress has not commented. (C) Cover Media