The guard took a pen to Anna Leporskaya’s avant-garde painting Three Figures on his first day working at the Boris Yeltsin Presidential Center in the city of Yekaterinburg.

The piece, which was painted between 1932 and 1934, is insured for 75 million roubles – around €880,000 or £740,000.

Anna Reshetkina, curator of the exhibition, said the guard’s “motives are still unknown but the administration believes it was some kind of a lapse in sanity”, The Guardian reports.

The work is now being restored at a cost of up to 250,000 roubles (around €3,000 or £2,500).