"Today we submitted constitutional amendments to the paper submitted to us by the Special Envoy and we consider such amendments to be an integral part of this paper," Syrian ambassador Bashar Ja'afari told reporters after two meetings with UN Special Envoy Staffan de Mistura in Geneva on Monday.
"The dialogue was rich in ideas... We agreed to meet tomorrow at noon," he said, without taking questions, Reuters reported.
The talks at UN headquarters in Geneva aim to halt a conflict that has allowed for the rise of the Daesh (ISIL) group, sucked in regional and major powers and created the world's worst refugee crisis.
De Mistura now says 400,000 people have been killed in the war, far higher than the previous UN toll, usually given as 250,000. He said he had no proof of the higher figure but the estimate of 250,000 was two years old and no longer valid.