A top Russian diplomat has accused the United States of promoting unverified reports about chemical weapons attacks in Syria in order to cloud Russia's peace initiatives.

Russia is hosting Syria peace talks in the Black Sea resort of Sochi next week that some Syrian opposition figures said will run counter to U.N. peace initiatives.

Deputy Foreign Minister Sergei Ryabkov said in an interview with the Interfax news agency on Wednesday that the U.S. is promoting "rigged, unverified reports" of the alleged use of chemical weapons in Syria to hamper Russia's peace efforts.

Ryabkov's remarks came a day after U.S. Secretary of State Rex Tillerson said Moscow "ultimately bears responsibility for the victims" of a new suspected chemical attack outside the Syrian capital Damascus.