Relatives of two Australian Greenpeace activists detained with 28 others in Russia over an Arctic oil drilling protest have told of their heartbreak over their extended detention.

Tasmanian Colin Russell, 59, and Sydney resident Alex Harris, 27, are among the so-called Arctic 30 charged with piracy and hooliganism over a protest against the oil drilling in September.

Russian authorities announced on Friday they would apply for a three-month extension to their detention.

The so-called “Arctic 30” were detained when the Russian Coast Guard boarded their Dutch-flagged Greenpeace vessel after several activists scaled a state-owned oil platform on September 18 in a protest.

Russia has since put the 30 people in prisons in Saint Petersburg pending trial after moving them from the Arctic Circle city of Murmansk.

Mr Russell’s daughter Maddy broke down on Saturday as she spoke about not having her father back by Christmas during a support rally near the Sydney Harbour Bridge.

“We’ve had only one call in the whole 60 days since this happened,” Ms Russell, 24, said.

“I had a hope in the back of my mind that he would be home in time for Christmas and I don’t know what to make of it now.”

Ms Harris, who is a UK citizen living in Manly in Sydney’s north, has been writing letters to her cousin and housemate Gemma.

“As she writes each letter, each time I read them she becomes stronger and stronger,” Gemma said.

As part of a global day of solidarity, about a hundred people gathered in Hickson Road Reserve holding up big white letters that spelled out “Free the Arctic 30”.

They also released 30 doves, one for each person detained.

Star power

Oscar-winning actress Marion Cotillard briefly caged herself near Paris’s Louvre museum to demand the freeing of the jailed activists.

Cotillard, the star of the acclaimed 2007 film La Vie en Rose on French singer Edith Piaf, entered the cage and held a banner proclaiming: “I am a climate defender.”

She joined Greenpeace activists all dressed in red.

“There are people who have the courage to defend our planet and who put themselves into great trouble,” she said, calling the detention “absolutely absurd and crazy”.

The symbolic protest was staged in the heart of Paris at the Palais Royal complex, where the state theatre Comedie Francaise is located.

Several serving and former ministers and celebrities from the world of arts showed up to express their support.