Since two jihadist killers murdered a dozen people at the leftist weekly magazine's offices on January 7 in retribution for the publication of images mocking the prophet Muhammad, the finances of Charlie Hebdo have been transformed.

The cash pile is reportedly as high as $US33 million ($45 million), but management puts it at $US18 million, Vanity Fair reports.

Subscriptions have multiplied from about 10,000 to 20 times that number, and donations from Google, the French government and sympathisers around the world have poured in. Eight million copies of the post-massacre edition were sold, an increase of 13,000 per cent on previous sales.

But what is an anti-capitalist publication to do with such wealth in a culture where money is a dirty word and the President gained office by declaring war on the world of finance?

Or, as the surviving staff asked in a manifesto published in the daily Le Monde: "How are we to escape the poison of the millions that, through exceptional sales and also donations and subscriptions, have fallen into the pockets of Charlie?"

One staff member, cartoonist Renald Luzier, who is known as Luz, has said the paper is in post-traumatic shock.

One of the concerns relates to the magazine ownership since the massacre.

The parents of murdered editorial director and cartoonist Stephane Charbonnier now own a 40 per cent stake; writer and cartoonist Laurent Sourisseau also holds 40 per cent, while finance director Eric Portheault owns the rest.

Many staff are unhappy that the new wealth is held in so few hands.

"We refuse that a handful of individuals take control, either total or partial, in absolute contempt for those who make and support [the publication]," they wrote.

The staff want a more collective approach.

The paper should be turned into a co-operative "in line with the social economy of solidarity that Charlie backs".

They want all staffers to be given a stake but without any possibility of personally profiting from their shareholdings, so that the "incredible" financial reserves can help ensure the publication's survival for decades to come.

Journalist Patrick Pelloux, who is also an emergency department doctor, was the first medic on the massacre scene.

He told Roger Cohen of Vanity Fair: "It is not through our talent that we got this money. It is through a massacre. And we need a collective system to do the right thing with it."

How much money should go to the families of the victims, whether to set up a foundation to defend freedom of expression and how to guarantee the paper's financial future were some of the challenges to be resolved, and this would take at least a year, Pelloux said.

Luz, who is seen as the soul of the publication, has said he will resign in September.

"The money we have is absurd. The number of readers we have is absurd. All the support we have is magnificent but also absurd. I do not know how we will manage to emerge from all this absurdity," he was reported as saying.