MOSCOW: Russia said on Tuesday it had stepped up airstrikes against Islamist militants in Syria with long-range bombers and cruise missiles after the Kremlin said it wanted retribution for those responsible for blowing up a Russian airliner over Egypt.

President Vladimir Putin, visiting the defence ministry's command center in Moscow on Tuesday evening, was told by military chiefs that the air force had carried out around 2,300 sorties in Syria in the last 48 days and that it would bolster its strike force, which consists of around 50 planes and helicopters, with a further 37 aircraft.

Putin, in footage broadcast earlier on Tuesday, had vowed to hunt down those responsible for blowing up a Russian airliner over Egypt and intensify airstrikes against Islamists in Syria, after the Kremlin concluded a bomb had destroyed the plane last month, killing 224 people.

Speaking four days after Islamist gunmen and bombers killed at least 129 people in Paris, Putin ordered the Russian navy to establish contact with a French naval force headed by an aircraft carrier in the region and to treat them as allies.

"We need to work out a plan with them of joint sea and air actions," Putin told military chiefs.

The Kremlin said in a separate statement that Putin and his French counterpart Francois Hollande had spoken on the phone on Tuesday and agreed to boost coordination of their military actions in Syria.

Hollande is due in Moscow on Nov. 26 to discuss the fight against Islamic State there, the presidency said in a statement on Tuesday.