TEHRAN— Nasser Kanaani, spokesman for Iran's Foreign Ministry, has harshly denounced the terrorist attack outside Russia's embassy in Kabul, which murdered two Russian diplomats and a number of Afghans.

Kanaani offered condolences to the Russian government and the families of the two diplomats. He also sympathized with the Afghan families who lost members in the blast.

The Foreign Ministry spokesman also requested that Afghan officials take more stringent steps to secure foreign embassies and diplomatic posts in the country.

Two Russian embassy staffers in Kabul were among six persons killed when a suicide bomber detonated explosives at the embassy's door, injuring at least ten others, the Russian Foreign Ministry and Afghan officials said on Monday.

The attack was claimed by the Islamic State (Daesh) on its Telegram channel.

The attacker was fatally shot by armed security guards as he neared the gate, according to police, in one of the first such attacks since the Taliban took power last year.

"The suicide attacker before reaching the target, was recognized and shot by Russian embassy (Taliban) guards ... there is no information about casualties yet," Mawlawi Sabir, the head of the police district where the attack took place, told Reuters.