Police have reportedly launched an investigation after a guitar was allegedly stolen from Constantine Maroulis' band during a charity event in New York.

A bass is said to have been snatched from the musicians following Maroulis' performance at the Love Heals gala in New York's Hamptons on Saturday (19Jul14).

A source tells New York Post gossip column Page Six that police officers are attempting to track down the culprit using pictures taken at the event.

The insider says, "Some idiot stole the bass guitar from the band... The thief was no genius - he was photographed (at the event). The cops are confident he will be tracked down."

Guests at the event included socialite Nicky Hilton.