Russia has reached a provisional agreement with the United States on the conditions of ceasefire in war-hit Syria, U.S. Secretary of State John Kerry reportedly said Sunday.

Kerry and Russian Foreign Minister Sergei Lavrov held a telephonic conversation to discuss conditions to implement ceasefire in Syria where hundreds of thousands people have been killed in five-year-long civil war, Reuters quoted Russia's Foreign Ministry as saying.

"We have reached a provisional agreement, in principle, on the terms of the cessation of hostilities that could begin in the coming days," Agence-France Presse quoted Kerry as saying. The international community was "closer to a ceasefire today than we have been," he added.

Russia has been backing Syrian President Bashar al-Assad's government forces with its air strikes to free rebel-held areas in the Middle-Eastern country.

The Syrian civil war, which started in 2011, has led to the death of at least 470,000 people as of 2015, The Guardian reported, citing the NGO Syrian Centre for Policy Research (SCPR).

Of the total casualties reported by SCPR, at least 400,000 were killed in the conflict while the rest died due to lack of adequate food, healthcare, medicine, clean water, sanitation and proper housing, as several thousands were displaced in the war-hit nation.