Michael Arndt and William Monahan have won top honours at the Writers Guild of America's (WGA) simultaneous annual awards nights in Los Angeles and New York on Sunday night.

Arndt took the original screenplay prize for the comedy Little Miss Sunshine, while Monahan won the adapted screenplay category for crime thriller The Departed, based on Alan Mak and Felix Chong's Hong Kong hit Infernal Affairs.

Amy berg took the documentary screenplay prize for the paedophilia film Deliver Us From Evil.

The dual events hosted by the WGA's West and East Coast chapters took place at the Hyatt Regency Century Plaza Hotel in Los Angeles and the Hudson Theatre in New York.