MOSCOW (Reuters) - Russia has issued an international arrest warrant for Mikhail Khodorkovsky on suspicion of ordering a contract killing, investigators said on Wednesday, prompting the former oil tycoon to declare the Kremlin had gone mad.

Former Russian tycoon Mikhail Khodorkovsky speaks during a Reuters Newsmaker event at Canary Wharf in London, Britain, November 26, 2015. REUTERS/Peter Nicholls

The move came a day after armed police raided the Moscow offices of a pro-democracy movement founded by Khodorkovsky, one of President Vladimir Putin’s most outspoken critics.

Khodorkovsky, once Russia’s richest man, was pardoned by Putin in 2013 and freed after a decade in jail on fraud charges he says were politically motivated. He has angered the Kremlin in recent months with critical statements.

He accused Putin in November of leading Russia into a 1970s Soviet-style period of stagnation that could eventually trigger the country’s collapse. Earlier this month he said a peaceful revolution was “inevitable”

Russian investigators said they had concluded that Khodorkovsky, then head of the now defunct Yukos oil company, had ordered subordinates to kill Vladimir Petukhov, the mayor of Nefteyugansk, a Siberian oil town, in 1998.

Petukhov was shot dead by a gunman near his office.

Vladimir Markin, a spokesman for Russia’s Investigative Committee, said Khodorkovsky’s motive for allegedly ordering the official’s murder was related to Petukhov’s demands for Yukos to pay local taxes he said it was evading.

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“WANTED FUGITIVE”

Markin said Khodorkovsky had also ordered the killing of a businessman, Evgeny Rybin, who was shot at in 1998 and had his car bombed the following year but survived.

“For the investigation, it is completely obvious that these crimes were carried out for mercenary motives,” Markin said in a statement. “We declare Mikhail Khodorkovsky a wanted fugitive internationally.”

Khodorkovsky denies the allegations and condemned the decision, suggesting it was politically motivated.

“They have gone mad,” he said of the Kremlin, saying his arrest in absentia had been approved “without any obvious facts.”

He told a news conference earlier this month that the Kremlin had been using the Petukhov murder case against him since 2003 to punish him for speaking out about corruption in Russia.

“The murder was solved that same year, 1998, and the presumed perpetrators were arrested. (But) for some reason, they were then freed and were subsequently killed,” he said.

Khodorkovsky left Russia immediately after being released in 2013, and now spends his time mostly in London and Switzerland.

A spokesman for Putin said there was no contradiction between the president pardoning Khodorkovsky and the businessman then being declared an international fugitive.

“The head of state takes decisions about pardoning people on the basis of appeals, but a decision about an investigation or declaring someone a fugitive ... is not taken by him. It is taken by investigators,” said the spokesman.