A Russian judge has refused to free Australian Greenpeace activist Colin Russell, who is among 30 people arrested over a protest against Arctic oil drilling.

The Tasmanian radio operator on board the Arctic Sunrise was arrested in September after some of the activists tried to scale the Prirazlomnaya oil rig.

A court in St Petersburg has now ruled that Russel must now stay in jail until February 24.

The 59-year-old was led into court in handcuffs and confined to a defendant's cage.

"I'm here to defend my innocence. I have not committed a crime," he said.

"I have not lifted a hand in an angry manner ever in my life. I have never been violent.

"I don't understand the reasons why I'm being detained. I say that my human rights have been violated very, very wrongly and badly."

Russian citizens granted bail

In what some observers have seen as the first sign of leniency for the 30 people arrested, the ship's doctor and a freelance journalist - both Russian citizens - have been granted bail.

The court ruled that Yekaterina Zaspa, a Russian medic on the Arctic Sunrise who was not among those who tried to climb the rig, could be released on 2 million roubles ($65,000) bail.

The two bailed Russian activists didn't scale the oil platform in the September protest. ( AFP: Denis Sinyakov/Greenpeace )

The judge gave a similar ruling to Denis Sinyakov, a 36-year-old photographer who was on board the Arctic Sunrise when Russian coastguards forced their way on after the protests.

It was not immediately clear why the courts agreed to release the two Russians on bail, but to extend the term of custody for Russell, who had not tried to scale the rig.

Others in the group will appear in court in the coming days.

Greenpeace spokesman Reece Turner says Russell's family are concerned about the 59-year-old's well-being.

"I know it's been really hard for the family to hear about how tough it is for Colin inside. We know that he hasn't been getting adequate food, that he's been losing a lot of weight. That it's been cold and he's really lonely and isolated," Mr Turner said.

"What I think though, is the hardest thing, is the uncertainty; not knowing when Colin can come home."

Maritime Court to rule on case on Friday

The 30 arrested face up to seven years in jail if convicted of hooliganism.

Western leaders including German chancellor Angela Merkel have expressed concern to Russian president Vladimir Putin over the case and Western celebrities have voiced support for the Greenpeace campaigners.

Ex-Beatle Paul McCartney has asked Putin to help secure their release.

Greenpeace is also hoping the protesters' release may be secured on Friday when the Hamburg-based International Tribunal for the Law of the Sea rules in a case the Netherlands lodged against Russia.

But Russia is boycotting the case, which means it is unlikely to adhere to the court's ruling.

ABC/Reuters