Russian President Vladimir Putin on Tuesday accused foreign "forces" of using radical Islam to sow discord in Russia, after a Muslim suicide bomber killed six on a bus in southern Russia.

"Some political forces are using Islam or more precisely its radical strains...to weaken our state, to create in Russia zones of 'ethnic conflict ruled from outside,' to drive a wedge between different ethnic groups, inside the Muslim community, to inflame separatist sentiments in provinces," Putin said, without providing specifics.

Speaking at a meeting with Muslim clerics in the city of Ufa, some 1,500 kilometres (930 miles) east of Moscow, he said tension between the West and the Islamic world was on the rise.

"Someone is trying to use this issue to one's advantage, add logs to this fire," Putin said. "I would like to tell you: we are not interested in this."

On Monday, a 30-year-old woman from the volatile Russian North Caucasus region of Dagestan blew herself up on a bus in the southern city of Volgograd, killing six and injuring more than 30.

During his decade in power, Putin has repeatedly vowed to root out insurgency in the Caucasus, where the Kremlin fought two wars against separatists in Chechnya over the past 20 years,although the unrest shows little sign of abating.