Avril Lavigne went on a girls-only trip to Las Vegas.

The 'Girlfriend' singer - who filed for divorce from her estranged husband Deryck Whibley in October 2009 - recently whisked away some of her closest female friends for a five-day break in 'Sin City' to party and have fun.

A source told America's Star magazine: "All she wanted was a girls' weekend. She had a strict no-boys-allowed rule. She needed to let loose. She'd had it up to there dealing with men."

Avril splashed out over $750 a night for the women to stay at the luxurious Vdara hotel and spa in the new CityCenter complex.

On one night out to the Bank nightclub, which is located inside the Bellagio hotel, the 25-year-old pop star treated fellow revellers to a short impromptu sing-along as she partied with friends and ignored the advances of any men.

The source added: "They took shots of Patron tequila when they weren't drinking vodka. She couldn't have cared less about any of the men ogling her. They closed down the clubs every night they went out. They had a blast. Then for the hangovers, they hit Vdara's spa before doing it all again."