And finally… the missing ink

It has been alleged that the ink was used in an incident being held up by Kremlin critics as evidence of a deep-seated culture of corruption.

Independent councillor Yelena Selkova, posted a video on social media displaying how the figures on the contract for installing a new lift in a residential building vanished when it was held to up to a flame.

The construction work was officially valued at 2.6 million roubles (£29,000), The Times reports.

Ms Selkova said it was likely that officials at the government agency responsible for housing repairs had intended to erase and replace the sum of money with a new, substantially higher price after it had been approved by other Moscow councillors. 

She suspects that the monetary difference would have been distributed between officials and the contractors. She alleged that this was not the first time that housing officials have used invisible ink for such scams.

Invisible ink has been reportedly been used at polling stations to ensure officials secure their desired outcome at elections. In one incident in 2011, after a voter complained, an election official wrote, “I don’t believe you” on a ballot paper to prove that everything was in order. The words vanished soon after.