Greenpeace organised protests in 263 cities around the world on Saturday to mark two months since 30 of its environmental activists were jailed in Russia over a demonstration against Arctic drilling.

The group said it hoped thousands of people would take part in the protests, which were taking place from London and Berlin to Delhi and Buenos Aires.

In a case that has sparked an international outcry, the crewmembers of Greenpeace's Arctic Sunrise ship were detained on September 18 after several of them scaled an oil platform run by Russian state-owned energy giant Gazprom.

British supporters staged peaceful protests at some 70 petrol stations run by Anglo-Dutch energy company Shell, which has links to Gazprom, Greenpeace said.

In the German cities of Berlin, Munich and Frankfurt, protesters were planning lantern-lit marches to Russian consulates, while in Budapest, protesters used candles to spell out the words "free the Arctic 30" in huge letters.

In Delhi, activists stood inside a giant cage during a 30-hour protest.

John Sauven, executive director of Greenpeace UK, said: "28 activists and two journalists remain in detention after the seizure of our ship Arctic Sunrise by armed Russian Federal Security Bureau agents.

"(They) now face exceptionally serious charges of hooliganism and piracy, accusations with no merit in either Russian or international law."

Shell was being targeted in Britain because of its partnership with Gazprom, he added, warning that this could become a "corporate millstone" for the Anglo-Dutch firm.

A Shell spokesman declined to comment on the reasons for the protest.

Celebrities including Madonna and ex-Beatle Paul McCartney have called on Russia to free the Greenpeace crew, who are awaiting trial in prisons in St Petersburg.

Russia's Investigative Committee said last month it was softening the charges against the crewmembers -- who come from 19 different countries -- from piracy to hooliganism, which carries a maximum sentence of seven years.

Greenpeace says the piracy charge was never formally lifted.