Fighting continued to intensify a week into a new Russian-backed Syrian government offensive to capture rebel-held eastern Aleppo and crush the last urban stronghold of a revolt against Syrian President Bashar al-Assad that began in 2011.
Moscow and Assad spurned a US-Russian brokered ceasefire agreed to this month and launched attacks on rebel-held areas in Aleppo in potentially the most decisive battle in the Syrian civil war.
US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov spoke by telephone for a third straight day, with the top Russian diplomat saying Moscow was ready to consider more ways to normalize the situation in Aleppo.
But Lavrov criticized Washington's failure to separate moderate rebel groups from those the Russians call terrorists, which had allowed forces led by the group formerly known as the Nusra front to violate the US-Russian truce agreed on Sept. 9.
In a 40-minute discussion with Syrians, diplomats and others on the sidelines of the United Nations General Assembly meeting in New York last week, Kerry said the administration had failed to make any threat of military force that give him leverage with Russia.
Syrian government forces and rebels fought battles on September 30 in the city center and north of Aleppo, where government troops had recaptured a Palestinian refugee camp on September 28 that already had changed hands once since the start of the attack.