Written by By Zamira Rahim, CNN

Street artist Banksy may have painted himself into a corner. The anonymous art star has been forced to cancel plans to give free works to voters in parts of the UK, after the police launched an investigation.

Banksy's website offered prints of one of his most famous images, "Girl with balloon," to Bristol-based residents who voted against Conservative Party candidates in this week's general election.

The picture shows a young girl stretching out her hand as a heart-shaped balloon, decorated with a Union Jack flag, flies away. In the original painting, the balloon was red.

Voters were encouraged to send in a photo of their completed ballot paper, in exchange for a print, but the offer appeared to be illegal under UK law, and Avon and Somerset Police received a number of complaints.

"It is a criminal offence under the Representation of People Act 1983 for any voter to accept or agree to accept a gift or similar in return for voting or refraining from voting," the force said in a statement. "We can confirm we're investigating the offer."

A spokesman told CNN "all election complaints are looked at locally."

Banksy has now withdrawn the controversial offer.