The Labour Party launched the 'Borrisstoppers' advert in the Evening Standard on Tuesday evening, designed to highlight Boris Johnson's above-inflation fare hikes.
Funding for the ad comes from Labour's 'chicken fundraising appeal'.
Labour claims that Johnson is refusing to engage Ken Livingstone - Labour's candidate in the pending London 2012 mayoral election - in a debate, and launched the 'chicken fundraising appeal' last Wednesday in response.
"This ad makes a serious point in an eye-catching way - a pickpocket is operating on public transport but unfortunately it is the Tory Mayor. He is making your pockets and purses lighter through rocketing fares. His decision to force Londoners to pay sky high fares is putting huge pressure on millions of people who are already feeling squeezed by the rising cost of living in the capital", a spokesperson for Livingstone said.