Georgian President Mikhail Saakashvili has called an emergency meeting of the country's national security council following the death of Prime Minister Zurab Zhvania overnight. Mr. Zhvania's bodyguards found him dead in a friend's apartment, apparently the victim of a natural gas leak.

A probe into Mr. Zhvania's death is already under way, but Georgia's Interior Minister, Vano Merabishvili, has said there are no signs of foul play and that it appears to have been a "tragic accident."

Interfax news agency quotes the head of the city's gas supplier as saying high levels of carbon monoxide were registered in the apartment, where Mr. Zhvania was drinking and playing backgammon with a regional deputy governor.

Mr. Zhvania's bodyguards discovered the bodies of the two men in separate rooms after they were unable to reach the prime minister on his mobile phone and broke down the apartment door to enter.

Convening an emergency session of parliament in Tbilisi Thursday, Georgian President Mikhail Saakashvili described Mr. Zhvania's death as a huge blow for Georgia and for him, personally. His eyes red with tears, Mr. Saakashvili said he had lost his closest friend and most loyal advisor.

A former ally of ousted Georgian President Eduard Shevardnadze, Mr. Zhvania later joined forces with Mr. Saakashvili and was an instrumental player in Georgia's peaceful Rose Revolution that promised pro-Western reform.

Political analyst Ghia Nodia, who heads the Caucasus Institute for Peace and Democracy in Tbilisi, says Mr. Zhvania will be a hard man to replace.

"[Mr.] Saakashvili was more a person who would push for change and make difficult or strong decisions, but Mr. Zhvania was the main person to implement the policy," said Ghia Nodia.

Mr. Nodia also says it will be hard to find someone with Mr. Zhvania's political skill and efficiency. As he put it, "there is no one of his magnitude in Georgia today." But Mr. Nodia says he still does not think this will reverse the movement toward political reform in Georgia.

"No, they will of course go ahead," he said. "I don't think that it's a matter of reforms being slowed down. It's rather a matter of how orderly and consistent they will be."

Russian President Vladimir Putin sent condolences from the Kremlin, describing Mr. Zhvania as a "champion" of good relations between Georgia and neighboring Russia.

Household gas poisonings are common in the former Soviet Republic, with people often reduced to setting up dangerous make-shift heaters running off gas canisters, due to Georgia's still erratic power supply.