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.

Ukraine lost eight soldiers Wednesday in a dramatic spike in fighting with pro-Russian gunmen that further imperiled a truce Washington's top European envoy is desperately trying to salvage in Kiev.

Separatist rebels also reported the death of two fighters and a civilian in shelling across the eastern industrial heartland of the former Soviet nation that took a decisive tilt toward the West more than a year ago.

The Iran nuclear deal paves the way for a "broad" coalition to fight the Islamic State group, Russian Foreign Minister Sergei Lavrov said Tuesday.

"It removes the barriers -- largely artificial -- on the way to a broad coalition to fight the Islamic State (IS) and other terrorist groups," Lavrov said in a statement on the ministry's website.

Moscow officials on Tuesday rejected a proposal to put up a memorial for opposition politician Boris Nemtsov on the bridge where he was shot dead.

Such a monument would be "commemorating not the memory of a man, but the murder itself. And do we need this?" said the head of the city government's memorial commission, Lev Lavrenov, cited by Interfax news agency.

Georgia decried on Tuesday Moscow's "creeping annexation" of its territory after Russian border guards moved border markers further into Tbilisi-controlled area, leaving a portion of an international oil pipeline in territory under Russian control.

The move left a small portion of the Baku-Supsa pipeline, which transports Caspian oil destined for Western markets, under Russia's effective control.

Two pilots were killed when a strategic bomber with seven people on board crashed in far eastern Russia on Tuesday, the defense ministry said, the latest in a string of military aircraft accidents.

"The search and rescue team of the eastern military district has found where two members of the Tu-95 bomber landed," the Russian defense ministry said in a statement.

Iran and major powers headed into another late night of talks Monday on a deal to rein in Tehran's nuclear ambitions, as negotiators struggled to overcome the remaining few obstacles.

The White House said the marathon discussions in Vienna had "made genuine progress" but suggested they would stretch beyond a Monday night deadline.

Russian investigators said Monday that a Ukrainian pilot controversially detained in Moscow faces up to 25 years in prison for her alleged involvement in the killing of two Russian journalists.

Nadezhda Savchenko, Ukraine's first female military pilot, has been accused of abetting the deaths of Russian journalists Igor Kornelyuk and Anton Voloshin, who were killed by mortar fire in eastern Ukraine last summer.

Russia on Monday said the state news agency Rossiya Segodnya had had a bank account closed in London in a move that it said was connected to sanctions over Ukraine.

The foreign ministry said the "closure" of a Barclay's bank account on July 8 was linked to sanctions against the agency's head Dmitry Kiselyov over Ukraine, adding it was demanding an explanation from the British authorities.

Russia is considering direct deliveries of fuel to Greece to help prop up its economy, Energy Minister Alexander Novak said Sunday, quoted by Russian news agencies.

"Russia intends to support the revival of Greece's economy by broadening cooperation in the energy sector," Novak told journalists, quoted by RIA Novosti news agency.