It has become a sinister symbol marking support for Russia's barbaric invasion of Ukraine.

First seen on tanks and armoured vehicles on the battlefield, the letter Z has since been adopted for propaganda purposes by Vladimir Putin's supporters back home.

It has appeared on cars, clothing and signs and in images such as a sick photo of a Z reportedly made by Russian soldiers from the badges of Ukrainian troops killed in action.

Russian gymnast Ivan Kuliak, 20, is facing disciplinary action for taping a Z to his kit during a medal ceremony at a World Cup event in Qatar.

The bronze medallist provoked outrage when he then stood next to the Ukrainian who won gold, Illia Kovtun.