Street artist and provocateur Banksy has landed in hot water over his latest project, which has been timed to coincide with the UK general election.

Posting on his website, the artist is offering to send a “complimentary gift” in the form of an “exclusive new Banksy print” to voters in six Bristol constituencies who send in a photograph of their ballot papers from the 8 June election showing they voted against the Conservative candidate.

Voters in the Bristol North West, Bristol West, North Somerset, Thornbury, Kingswood and Filton constituencies who send in photos of their anti-Tory votes will receive a Banksy artwork, which is due for release on 9 June. The “souvenir piece of campaign material” is based on his popular “girl with a balloon” image but features a Union Jack inside the balloon.

What first appears as a rebellious political statement may actually constitute a violation of electoral law. By inviting voters to share images of their ballot papers Banksy may be contravening strict laws to safeguard the secrecy of votes. It has even been suggested that the stunt could break anti-bribery rules.

Election secrecy laws are sacrosanct in the UK. According to Section 66 of the Representation of the People Act 1983, it is a criminal offence to “directly or indirectly induce a voter to display his ballot paper after he has marked it so as to make known to any person the referendum answer for which he has or has not voted”.

Prior to local elections held in May 2014, the Electoral Commission even issued a warning to voters contemplating ballot selfies inside polling stations. “Given the risk that someone taking a photo inside a polling station may be in breach of the law, whether intentionally or not, our advice is that you should not allow photos to be taken inside polling stations”, an electoral administration bulletin issued on 29 April 2014 reads.

A “lawyer’s note” accompanying the “UK Election Souvenir Special” invitation on Banksy’s website assures that the print “is in no way meant to influence the choices of the electorate” and “is for amusement purposes only”.

The Conservatives have declined to comment on Banksy’s offer.