The Latest on the conflict in Syria (all times local):

11:15 a.m.

Russian Foreign Minister Sergey Lavrov is hosting the foreign ministers of Syria and Iran in Moscow as the Syrian army's siege of the rebel-held districts of the city of Aleppo continues.

Lavrov said in televised remarks on Friday at the start of the talks that Russia will keep supporting the Syrian government while the West is considering news sanctions to put pressure on both countries to halt an offense against rebel-held parts of Aleppo, which had drawn international outrage.

Lavrov will talk with with Syrian Foreign Minister Walid al-Moallem and Iran's Mohammad Javad Zarif separately before the three of them sit down for three-way talks later Friday. Iran is another key backer of Syrian President Bashar Assad.

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10:45 a.m.

Syrian rebel groups say they have launched a large-scale offensive to break the government's siege of eastern Aleppo, a contested city in the north of the country and the current focal point of the six-year war.

The Islamic Front rebel coalition announced on Twitter Friday morning that the ultraconservative Ahrar al-Sham group targeted a military airport to the east of the city with Grad rockets and destroyed a government position to the west of the city.

The Britain-based Syrian Observatory for Human Rights monitoring group said rebels detonated two car bombs against government positions to the city's southwest and attacked with more than 150 rockets.

Ammar Sakkar, the military spokesman for the Fastaqim faction inside the city said "all the revolutionary factions, without exception, are participating in the battle."