Russia's leaders are trying to stem the worst economic crisis in at least a decade and investors are watching for any signs of rising crime or discontent.

Moscow Chief Prosecutor Yuri Syomin said overall crime levels fell in 2008 but that there had been a spike in violent crime last month, which he linked to the economic crisis.

"If life becomes worse, then crime will rise," Syomin told reporters. "One of the most significant negative consequences of the crisis could be a change in crime trends."

Murders rose 16 percent in Moscow last month while fatal assaults soared 44 percent, Syomin said. It was not clear which months he was comparing with.

"These crimes are the ones that could rise further," he said. "Our aim is to concentrate on anti-crisis measures."

Syomin said immigrants -- who flocked to Moscow from former Soviet republics during the boom years to work on construction sites and in menial jobs -- were responsible for a disproportionate share of the increase.

Russia's $1.7 trillion economy is set to contract this year for the first time in a decade as the prices of Russia's main exports, notably oil, have tumbled.

The swift decline in Russia's economic fortunes, after a decade of spectacular growth that boosted living standards for many sections of society, has raised concerns about stability in the world's biggest producer of natural resources.

Russia said 5.8 million people were out of work in December and local media say the number of unemployed is soaring as businesses try to survive by slashing costs.

Some analysts say the official figures are not complete as tens of thousands more Russians have been forced to take unpaid holiday and thus do not show up in the unemployment data. Wage arrears are also on the rise.

Crime soared in Moscow after the 1991 fall of the Soviet Union, earning the city a wild reputation as a den of iniquity where killings were commonplace.