Pop star Justin Bieber has been photographed reportedly drinking beer at a nightclub, breaching strict age-limit laws.

The "Baby" hitmaker, 20, headed to the popular Bootsy Bellows nightclub in West Hollywood, California this week with controversial singer Chris Brown and was snapped topless, clutching a bottle of lager as he chatted to a female reveller, reports contactmusic.com.

The legal age for drinking alcohol in the US is 21, and editors at Tmz.com report officials at the California Department of Alcoholic Beverage Control are investigating whether the venue's owners have breached conditions of their licence.

The nightclub is co-owned by actor David Arquette.

Bieber is currently at the centre of a driving under the influence (Dui) case following his arrest in Miami, Florida in January, and he is also facing prosecution in his native Canada over claims he lashed out at a limousine driver in December last year.