A foreign ministry official, quoted by the state's Qatar News Agency, did not name the Russians.

Moscow has been asking the Gulf Arab state to hand over two Russian intelligence agents sentenced to life imprisonment this year for killing an exiled Chechen rebel leader.

The Qatari official said the freed Russians would serve the rest of their jail terms in Russia. He said Qatar and Moscow had signed an accord on this issue.

In June, a Qatari court said Anatoly Belaskhov and Vasily Bogachev had killed Chechen rebel chief Salim Khan Yandarbiyev and two others with a car bomb, acting on an order from the Russian leadership to assassinate him.

Russia had at the time denied the men were responsible.

The attack shocked Qatar, which prides itself on its security and low crime rate, and sparked a diplomatic row with Russia.