Kovtun, a men's all-around bronze medallist at last year's World Championships, was pictured wearing the t-shirt in the Ukrainian national colours of yellow and blue.

Russia and its ally Belarus are not competing at the World Championships as part of the International Gymnastics Federation's (FIG) measures implemented in response to the invasion of Ukraine, in line with the recommendations of the International Olympic Committee.

The FIG published a new Code of Conduct outlining standards of behaviour expected from all participants in the sport, which included an explicit ban on "any kind of demonstration or political, religious or racial propaganda in any gymnastics competitions".

Podcast GymCastic reported that FIG supported the sentiments expressed by Kovtun, but asked the Ukrainian Gymnastics Federation for him not to wear the t-shirt as it is not permitted under the Code of Conduct.

However, the athlete has not received any penalty.

The update to the FIG Code of Conduct came following an incident at the FIG World Cup in Doha in March, the last event in which Russian and Belarusian athletes were able to compete under a neutral banner before a full ban was introduced.

Russian gymnast Ivan Kuliak wore the letter "Z", a symbol associated with the military operation in Ukraine, on his singlet during the competition and also during the medal ceremony for the parallel bars.

He has since been banned for one year by the Gymnastics Ethics Foundation for his action, although this is running alongside existing measures against Russian athletes.

The FIG has also prompted controversy through its decision to allow Russia and Belarus to attend its Congress in Istanbul.

The gathering has been moved from Sandefjord in Norway after it refused to welcome delegates from both countries, and at least seven European National Federations plan to boycott it.