MOSCOW, RUSSIA - Russia is ready to help Iran fight "terrorism", President Dmitry Medvedev said Monday, in a letter of condolence to his Iranian counterpart Mahmoud Ahmadinejad after a deadly attack on an elite force.

"The fight against the threat of terrorism and the extremism - wherever it comes from - requires all countries to join their forces," Medvedev said. "We are ready to cooperate with the Islamic Republic of Iran to counter these threats," he added.

His statement came after a suicide bomber killed 49 people in southeastern Iran on Sunday, including top commanders of the elite Revolutionary Guards. The bombing targeted one of the Islamic republic's most prestigious institutions in a hotbed region of Sunni insurgency against the Shiite Muslim regime.

Medvedev said he had learned of the attack with "indignation" and condemned "this new evildoing by extremists".

Russia has itself seen a spate of militant attacks this summer in the predominantly Muslim North Caucasus, where the Russian government has been long struggling to put down a low-level Islamist insurgency.

Moscow has the strongest ties to Iran of any major world power and is seen as a crucial player on the international standoff over its nuclear programme.