Russian President Vladimir Putin said on Tuesday that Iran had a right to a peaceful nuclear program but slammed as "unacceptable" its threats against its regional nemesis Israel.

"Iran is in a very difficult region," Putin told a televised question-and-answer session in Moscow.

Russian President Vladimir Putin said Tuesday he had always believed that Syrian strongman Bashar Assad should have implemented political reforms that could have averted the current bloodbath.

But Putin also stressed that he remained firmly opposed to outside intervention and implied that Russia's position on the crisis remained unchanged.

Iran has received a verbal invitation to attend the proposed peace conference on Syria, the Islamic Republic's deputy foreign minister said on Tuesday without specifying who extended the invitation.

"Ten days ago, we received a verbal invitation to take part in this conference," Iran's Deputy Foreign Minister Hossein Amir Abdollahian told reporters in Moscow.

Russia on Tuesday passed a bill imposing jail terms of up to three years on those who offend religious believers after an anti-Vladimir Putin stunt by punk band Pussy Riot in a church polarized the predominantly Orthodox country last year.

According to the bill passed in a 308-to-2 final vote, "public actions expressing clear disrespect for society and committed with the goal of offending religious feelings of the faithful" would be punishable with jail terms of up to one year in prison and fines of up to 300,000 rubles ($9,200).

Three policemen were killed and two passers-by were wounded when a pair of unidentified gunmen opened fire in Russia's restive region of Dagestan where the Kremlin faces an Islamist insurgency.

The gunmen killed the three Russian policemen on the spot, while the two passers-by caught up in the shootout were hospitalized, the Investigative Committee said.

Iran has ordered that Syria provide Hizbullah with advanced weapons; Israel will do all in its power to stop this transfer of weapons, the Israeli prime minister said.

Prime Minister Benjamin Netanyahu denied reports in the media on Monday of alleged Israeli forces operating in Syria.

British Foreign Secretary William Hague warned on Sunday that gains made by the regime in the Syrian conflict this week made it harder to organize a peace conference and to make it a success.

He said it was "worrying and depressing" that the so-called Geneva talks were not taking place this month, and repeated his warning that the world must do more to help the people of Syria.

Five people died when a helicopter on a commercial flight crashed and burst into flames in a remote region of Far Eastern Russia, the emergency situations ministry said Saturday.

Rescuers found the bodies of four crew members and one passenger in the burnt-out wreckage of the Mi-8 helicopter in the Khabarovsk region after a two-day search. The helicopter was carrying three tons of cargo, the ministry said.

Russian President Vladimir Putin and his wife Lyudmila on Thursday announced they have divorced after three decades of marriage, in a joint interview with state television after watching a ballet performance.

"It was a joint decision," Putin said during the interview with Rossia-24 television that ended years of speculation about the state of their marriage.

Some 200 Russian Islamists who back North Caucasus insurgents are fighting in Syria for al-Qaida, the head of the Russian security service (FSB) said Thursday, Russian news agencies reported.

"The fact that around 200 fighters from Russia are fighting on the side of the Caucasus Emirate under the flag of al-Qaida and other related structures provokes concern in Russia," the head of the FSB Alexander Bortnikov said at an international security forum in the central Russian city of Kazan.