Greenpeace activist Colin Russell hopes he’ll be back in Tasmania before the end of the year after Russia granted amnesty to the so-called Arctic 30 who had been facing hooliganism charges.

Mr Russell, 59, was defiant after being told he wouldn’t face trial, insisting he hadn’t done anything illegal.

“It’s more relief than joy,” the full-time Greenpeace employee told AAP from St Petersburg.

“I didn’t do anything wrong. I was illegally brought here and illegally detained.

“I think the hierarchy, the people in Moscow, have said they want this to end, so it could very well be next week that we are on our way (home).”

Mr Russell was among 28 activists and two journalists detained in September after Greenpeace scaled a state-owned oil platform to protest Russian energy exploration in the Arctic.

The 30 – including Brit Alexandra Harris, who lives in Sydney, and New Zealander Jon Beauchamp, from Adelaide – were initially charged with piracy before that was downgraded to hooliganism.

Ms Harris, 27, said it was strange to be forgiven “for a crime we didn’t commit”.

“But I am relieved and looking forward to moving on with my life,” she said.

However, Russia’s lower house on Wednesday approved a Kremlin-backed amnesty bill that ends their prosecution and will also set free two jailed members of the punk band Pussy Riot.

The bill, which commemorates 20 years since Russia ratified its current constitution, applies to people charged or convicted on hooliganism or mass riot offences.

The amnesty doesn’t require approval by the upper chamber of parliament and will be effective when published, which is likely to be on Thursday.

Mr Russell was the radio operator on board the Greenpeace vessel Arctic Sunrise.

He spent more than two months in jail before being released on bail in late November.

The Tasmanian expects to be able to leave St Petersburg, where he is celebrating with his wife Christine and daughter Madeleine, once the criminal investigation is formally wound up and immigration provides a visa.

But the fate of the Dutch-registered Arctic Sunrise, impounded in Murmansk, is less certain.

The international maritime court in November ordered Russia to release the Greenpeace ship and its crew in exchange for a $A5.3 million bond.

Mr Russell now wants Moscow to act.

He argues Australia complied with a similar International Tribunal for the Law of Sea order after escorting a Russian vessel to Perth.

“Russia accepted that ruling back in 2002 and here we are today and they don’t even want to acknowledge that tribunal exists.”

Despite his recent hardships, Mr Russell says he’ll be back on duty for Greenpeace after taking some time off.

Any oil spill was bad, but if one occurred under ice it would be disastrous, he said.

“We did go to the Arctic for a reason … and I truly believe we are doing the right thing,” he said.

“It will only take one disaster to ruin everything.

“I don’t see how they could contain it. How could they clean it up?”