A Brazilian artist has unveiled an unusual set of drawings depicting himself assassinating world leaders, including the Pope, former US President George W Bush, and the Queen.

The series of nine charcoal drawings by Gil Vicente has prompted outcry in Brazil since going on display at the opening of the Sao Paulo Art Biennial on Saturday.

In one picture, Vicente is standing, looking at the Pope face on as he aims a gun at his chest. In another picture, Vicente stands apparently unnoticed behind the Queen, who is seated with her hands clasped in her lap.

Other world leaders depicted in the series, called Inimigos (Enemies), include Iranian President Mahmoud Ahmadinejad, former Israeli prime minister Ariel Sharon and former UN Secretary General Kofi Annan.

The motivation behind Vicente’s drawings are his belief that the leaders have in some way been responsible for the deaths of other people without being held to account.

He said: “Because they kill so many other people, it would be a favour to kill them, understand? Why don’t people in power and in the elite die?”

Vincente has reacted angrily to suggestions from some critics, including the Brazilian bar association, that his artwork be pulled from the exhibition because of its violent subject matter.

In an interview with Agence France-Presse news agency, the artist said: “They claim it justifies crime. Stealing public money is not a crime? The reports on TV aren’t trying to justify crimes? Only my work is justification of crime?”

A spokesperson for the bar association said: "Even though a work of art freely expresses the creativity of its maker, without limits, there have to be limits to exhibiting it publicly."

The series is valued at around $260,000 and is currently on display in a hall in Sao Paulo's main Ibirapuera Park.