An exiled oligarch and fierce critic of Kazakhstan's regime, Mukhtar Ablyazov, was being held in France Thursday as he awaited possible extradition after his dramatic arrest in a Riviera villa.

The former Kazakh energy and trade minister, who became an opposition leader before fleeing the country over accusations he embezzled billions of dollars, was arrested Wednesday in a six-bedroom house near the resort of Cannes, on a warrant issued by Ukraine.

Solange Legras, prosecutor at the local court handling his case, told AFP the 50-year-old would likely be put in prison as authorities examine extradition requests against him and decide whether to deport him.

Once close to the Kazakh elite, Ablyazov fell out of favour and became a foe of strongman Nursultan Nazarbayev, who has ruled the ex-Soviet country for almost 22 years, bringing economic reforms but cracking down hard on dissent.

Ablyazov was jailed in 2002 for abuse of power and illegal business activities after co-founding and leading an opposition party, in a move widely seen as a bid to silence him.

He was quickly pardoned and released, though, and returned to finance where he had made his fortune, leading the Kazakh BTA Bank, which also had interests in Ukraine.

But in 2009, he fled to Britain amid accusations he stole billions of dollars in state and investor funds. He is believed to have stayed there until he was sentenced to 22 months in jail for contempt of court.

He did not surrender to the British authorities and is then thought to have moved to Italy before his arrest in the south of France.

Three countries want his extradition -- Kazakhstan, Russia and Ukraine, where BTA also had interests.

Legras said France and Kazakhstan do not have an extradition agreement, and had initially said that Russia may no longer want to pursue him.

But a Russian interior ministry spokesman told the Interfax news agency that Moscow was drawing up the documents required for demanding the extradition of Ablyazov.

The oligarch was arrested by 15 police officers in a dramatic raid on the villa he was renting in Mouans-Sartoux, as a helicopter hovered in case he decided to escape.

"There was no violence. There had been some risks (of violence) as he is protected by a kind of private militia," Legras said.

According to a police officer working on the case, who wished to remain anonymous, Ablyazov had been moving regularly between three different villas in a bid to avoid scrutiny, along with his sister, niece and house personnel.

Some of his family members have already been caught and deported back to Kazakhstan. His wife and six-year-old daughter were extradited from Italy in May without the right to appeal, sparking a huge scandal in the country.

In a statement in the Italian daily La Stampa, two more of his children called on French authorities not to extradite him to Ukraine.

"We know that Ukrainian authorities act on behalf of Kazakhstan, because our father is the most important political opponent to the dictator Nazarbayev," Madina and Madiyar Ablyazov wrote.

Peter Sahlas, a lawyer representing the oligarch's children, told AFP that Kazakhstan had put a lot of efforts into finding him, as he reportedly still bankrolls the domestic opposition and media.

"I suspect he was found thanks to these private methods. I know for instance that Kazakhstan employed an Israeli firm of private detectives."

In a statement, BTA Bank said it had provided information to French police to help them find and arrest Ablyazov.

Bruno Rebstock, the oligarch's lawyer, told AFP his client was "in fighting mode and determined", adding he would officially ask for his release in the next few days.