(QHA) - Veteran British musician Paul McCartney has appealed to Russian President Vladimir Putin to release Greenpeace activists jailed after mounting an abortive protest against oil drilling in the Arctic Sea, RIA Novosti reports. Beatles founder McCartney asked Putin to reunite the 28 activists and the two journalists accompanying them with their families in a letter posted Thursday to his official website. “Vladimir, millions of people in dozens of countries would be hugely grateful if you were to intervene to bring about an end to this affair,” McCartney wrote in the letter, dated October 14. A reported earlier, activists were detained in September after attempting to scale the oil platform of an affiliate of Russia’s state-controlled energy giant Gazprom. All 30 were originally accused of piracy, but investigators later downgraded the charge to hooliganism, a charge punishable by up to seven years in prison. McCartney, who is an outspoken animal rights activist, said that the protest was peaceful and not motivated by anti-Russian sentiment. He referenced the 1968 Beatles hit “Back in the USSR” in his plea for Putin’s clemency toward the Greenpeace activists.