The landmark deal on Iran's nuclear program that Russia helped steer through marathon talks is a diplomatic fillip for Moscow which will boost trade with Tehran but could also hit much-needed energy revenues, analysts said.

Iran and the P5+1 group -- Russia, the United States, China, Britain, France and Germany -- struck an agreement on Tuesday that would progressively lift economic sanctions against Tehran in exchange for limitations on its nuclear program.

Russian President Vladimir Putin said Thursday that establishing an international tribunal to prosecute those behind the downing of Malaysia Airlines flight MH17 over rebel-held east Ukraine would be counterproductive.

He made his comments in a telephone conversation with Prime Minister Mark Rutte of the Netherlands, whose citizens made up the majority of the 298 people killed in the July 17 disaster last year.

President Barack Obama spoke by phone Wednesday with Vladimir Putin, thanking his Russian counterpart for his role in reaching a deal on Iran's nuclear program.

U.S. ties with Russia have been strained to breaking point over the war in Ukraine, but Russia was an "important" part of the group of nations that negotiated the deal with Tehran.

President Vladimir Putin has signed off on a law that brings next year's Russian parliamentary elections forward by three months, a move some commentators said gives an unfair advantage to pro-Kremlin parties.

"The election of the seventh convocation of State Duma deputies will take place on the third Sunday of September 2016," the Kremlin said in a statement on Wednesday.

Russian President Vladimir Putin on Friday warned the Islamic State group is reaching into Afghanistan, as he hosted a regional security summit drawing to a close.

"We noted the growing activities of the IS group militants who have extended their tentacles into this country," Putin said at a press conference after a summit of the Shanghai Cooperation Organization (SCO) in the Russian city of Ufa.

Kiev said Tuesday that Russia had cut off electricity to Ukraine's rebel-run regions in what appears to be another sign that Moscow is losing interest in plans to splinter its neighbor.

Russian President Vladimir Putin has gone through an extended spell without peppering his speeches with mentions of a "New Russia" (Novorossiya) made up of Ukrainian lands that were once under tsarist control.

Russian President Vladimir Putin has pledged to support Syria's government "politically, economically and militarily," the war-torn country's Foreign Minister Walid Muallem said in Moscow on Monday.

"I received a promise from President Putin to support Syria politically, economically and militarily," Muallem said at a press conference with his Russian counterpart after meeting Putin.

Russian President Vladimir Putin on Wednesday extended a ban against most Western food imports for a year after EU foreign ministers agreed to prolong sanctions against Moscow over the Ukraine conflict until January 2016.

"The government turned to me with an appeal to extend the measures," Putin told a government meeting.

Japanese Prime Minister Shinzo Abe called on Russian President Vladimir Putin Wednesday to play a constructive role in finding "peaceful and diplomatic solutions" to the crisis in Ukraine, after the EU agreed to prolong sanctions against Russia.

During a 30-minute evening teleconference, Abe requested that Putin implement fully the Ukraine ceasefire deal agreed in February, Japan's foreign affairs ministry said in a statement.

Former Ukraine president Viktor Yanukovych has thanked Russian President Vladimir Putin for "saving my life" during the bloody demonstrations that led to his ouster.

Yanukovych, currently exiled in Russia, told the BBC that he would like to return to Ukraine one day and blamed the country's plight on the demonstrators who occupied Kiev's Maidan Square -- the focal point of the uprising against his rule.