As revealed in an upcoming BBC documentary series, On Thin Ice: Putin V Greenpeace, McCartney was moved by the plight of a group of climate activists after they were seized in Russia during a protest and thrown in jail in 2013.
The group were aiming to film an oil rush in Arctic Russian waters, but 28 of them were arrested on their ship the Arctic Sunrise and charged under piracy and hooliganism charges.
McCartney, who famously played in Moscow’s Red Square in 2003, wrote a personal letter to the Russian president, imploring him to release the campaigners.
"Forty-five years ago I wrote a song about Russia for The White Album [‘Back In The U.S.S.R.’], back when it wasn’t fashionable for English people to say nice things about your country,” he wrote.
“That song had one of my favourite Beatles lines in it: ‘Been away so long I hardly knew the place, gee it’s good to be back home.’”
“Could you make that come true for the Greenpeace prisoners?”
"It would be great if this misunderstanding could be resolved and the protesters can be home with their families.
Kremlin spokesman Dmitry Peskov said he only heard of the letter from media reports but had not received it, according to the state-run Itar-Tass news agency.
The prisoners served a three month sentence before being released.
