Moscow authorities have been forced to make an urgent amendment to a monument dedicated to Mikhail Kalashnikov, the inventor of the ubiquitous AK-47 assault rifle, just three days after its grand unveiling.

An elaborate monument which now sits behind a 30ft statue of the inventor was supposed to depict all the weapons he designed in his lifetime, but observant Russians quickly noticed that a Second World War German rifle was also included in the display.

The Sturmgewehr 44 (StG 44) assault rifle was used by Nazi troops and has now been removed from the monument, leaving a gaping hole in its place.

The mistake is made even more embarrassing due to the ostentatious unveiling ceremony which included a Russian Orthodox priest blessing the statue with holy water.

The sculptor, Salavat Shcherbakov, was forced to apologise on state-run Rossiya 24 channel. He said: “It looks like this [mistake] sneaked in from the internet.”

And the error caused additional controversy because of the accusations, made during Kalashnikov’s lifetime, that his most famous weapon copied the StG 44 design.

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Kalashnikov created the AK47 in 1947, five years after the German arms designer Hugo Schmeisser’s released the Nazi edition.