Russian investigators have asked a Moscow court to move US investor Michael Calvey, who is accused of fraud, from pre-trial jail to house arrest.

The surprise motion comes two months after Calvey, head of a multi-billion dollar equity firm that has invested in some of Russia's biggest companies, was detained in a case he says is driven by a rival shareholder out to discredit him.

Basmanny District Court spokeswoman Yunona Tsareva said the court will consider the petition by the Investigative Committee on Thursday.

A similar petition was filed for one of the other suspects, Alexei Kordichev.

Calvey asked several times to be released from behind bars to be with his family, including in a letter to President Vladimir Putin.

The court had previously denied his request. A bail hearing was initially scheduled for the end of this week.

Calvey's lawyer Dmitry Kletochkin told AFP that he had no information on the surprise development.

"I have not seen the motion," he said, adding that house arrest is "much better than to be detained."

Calvey's Baring Vostok private equity fund — which has been working in Russia since the 1990s — said it "hopes the court will give due consideration" to the request.

It added it hopes four others detained would also be released.   The lawyer for French national Philippe Delpal who was denied bail as recently as Tuesday evening, said he was perplexed as "the crime they were accused of is the same."

Calvey was arrested in February with five other individuals, and accused of defrauding Vostochny Bank of 2.5 billion rubles (USD 37.7 million).

The arrest shocked Western business circles, who warned it could further discourage the foreign investment Russia's economy badly needs.

Calvey and his firm maintain that the case is fabricated and related to a shareholder dispute.