Russia has deployed a new mobile intercontinental nuclear missile - the foundation, it says, of the country's nuclear and missile shield for the next century.

The first ten Topol-Ms have been put on full combat readiness in the Saratov region, southeast of Moscow.

The Russian defence minister, Igor Sergeyev, said the new missile system expected to total forty Topol-Ms would preserve Russia's security, territorial integrity and independence.

The BBC Moscow correspondent says the single warhead Topol-M is lightweight and designed to be fired from a vehicle, giving it better protection from any pre-emptive strike.

Our correspondent says its deployment comes at a time of deteriorating relations between Russia and the West, with Russia opposing the expansion of NATO, military intervention in former Yugoslavia and the recent air strikes against Iraq.