MOSCOW (AFP) - Russia said on Wednesday it had issued an international arrest warrant for top opposition leader Mikhail Khodorkovsky, as Moscow ramped up the pressure on a leading critic of President Vladimir Putin.

The announcement from the Investigative Committee, a top law enforcement body which reports directly to Putin, came nearly two years to the day since the Kremlin strongman stunned Russia by announcing that his political enemy, who had spent a decade in prison, would be pardoned and set free.

Khodorkovsky's supporters say the new move is aimed at silencing Putin's exiled foe.

Investigators earlier this month charged the former oil tycoon in absentia with organising the 1998 murder of a mayor in Siberia.

Khodorkovsky, 52, was also charged with the attempted murders of two other people.

Investigative Committee spokesman Vladimir Markin said in a statement that an international arrest warrant had been issued for the Kremlin critic, who lives abroad and spends much of his time in London.

"They've gone mad," Khodorkovsky shot back in a statement released by his opposition group Open Russia.

He said an order to have him arrested in absentia compared favourably to a new law that would allow Russian police to fire at women and children.

"And what's most important it will be safe for the public," he said.

His spokeswoman Kulle Pispanen dismissed the announcement as political pressure and said it would not affect the former head of bankrupt oil giant Yukos.

"Mikhail Borisovich will by no means limit his movements because of the hysterical actions of the Kremlin ghouls," Pispanen told AFP, referring to the former business magnate by his first name and patronymic.

Khodorkovsky's lawyer Vadim Klyuvgant said it was up to foreign countries to decide whether to comply with the warrant.

Speaking on Echo of Moscow radio, he called the arrest warrant announcement "another bout of fraudulent activities".

Putin's spokesman Dmitry Peskov insisted that there was no contradiction between the president's move to pardon the ex-tycoon and the arrest warrant.

On Tuesday, investigators raided the apartments of employees of Khodorkovsky's Moscow-based Open Russia group, set up to help nurture civil society in the country, as well as its offices.

The searches appeared tied to a 2003 case which led to the criminal prosecution of one of Russia's most powerful oligarchs and the dismemberment of his Yukos oil company which have become defining events in Putin's presidency.

The Investigative Committee has said it is also checking information provided in foreign courts by shareholders of now-bankrupt Yukos, who are seeking US$50 billion (S$70 billion) in damages from Russia and convinced a Paris appeals court to back the freezing of Russian assets in France.

Supporters and Khodorkovsky's staff ridiculed the raids.

"In revenge for the arrest of Russian property in France, the Investigative Committee arrested Kulle Pispanen's MacBook and iPhone, a letter to Father Christmas and a portrait of Khodorkovsky," Open Russia employee Maria Baronova said on Facebook.

Khodorkovsky spent a decade in prison on charges of tax evasion, fraud and embezzlement which he and his supporters say were trumped up in revenge for his political ambitions.

He was suddenly pardoned by Putin in 2013 and flown out of the country.

Khodorkovsky vowed to steer clear of politics upon his release from prison but the extent of his ambitions became apparent when in September 2014 he called on pro-European Russians to use his Open Russia platform to work together in the run-up to 2016 parliamentary polls to influence the fate of their country.

When investigators announced earlier this month they planned to press new charges against Khodorkovsky, he openly challenged the Kremlin, calling a news conference in London and saying that revolution in Russia was inevitable.

While in prison, Khodorkovsky frequently traded barbs with Putin, notably saying in 2010 he pitied a man who could only feel love for dogs.