LONDON (Reuters) - A seminal piece of work by the British street artist Banksy is set to be auctioned at Bonhams in London on Wednesday (June 29).

The spray painted Swat van has remained unseen by the public since his star-studded breakout show in Los Angeles in 2006 that was attended by Brad Pitt, Angelina Jolie, Cameron Diaz and Dennis Hopper. The painting on the van combines vicious Banksy's black humour with his anti-establishment message.

It depicts heavily armed agents being hoodwinked by a young boy on one side and Dorothy from The Wizard Of Oz on the other.

The work is on display in a courtyard outside Bonhams in London ahead of the auction that will also include works by Andy Warhol, Damien Hirst and Yayoi Kusama.