Moscow, Tehran and Ankara believe attempts to split Syria on ethnic and religious grounds to be unacceptable, Russian Foreign Minister Sergey Lavrov said on Saturday following a meeting with his Iranian and Turkish counterparts - Mohammad Javad Zarif and Mevlut Cavusoglu.
The US has "cover plans for reformatting the Middle East and plans for dividing Syria into parts", he said during a meeting with his counterparts from Iran and Turkey.
Lavrov said the three countries "must help the Syrians finish cleansing their country of terrorists".
The most recent Syria talks attended by the foreign ministers in Astana were held on March 16.
The three ministers reiterated their commitment to a peaceful resolution of the seven-year war in Syria, and dismissed criticism from some other nations that the Astana negotiations, which the three nations kick-started, were somehow harmful for the UN-sponsored negotiations in Geneva.
"Our cooperation in the fight against terrorism has been successful".
The three countries are working together to try to reduce the violence in Syria despite supporting opposing sides in the war.
Lavrov rejected USA statements on respecting Syria's territorial integrity as "only words" and said that Washington had designs for the country.
The Iranian, Russian and Turkish foreign ministers strongly condemned any use of chemical weapons in Syria and called on the Organization for the Prohibition of Chemical Weapons (OPCW) to "promptly and professionally" investigate into an alleged chemical attack in Syria. Rebels left the town a few days after the chemical attack there on April 7, in which dozens of people were reported killed.
The defense secretary said conflict between the two countries in Syria is "very likely... because Iran continues to do its proxy work there through Hezbollah".