The Syrian Democratic Forces said that attempts to negotiate a permanent ceasefire in the northern cities of Manbij and Kobani with Turkish-backed rebel groups through US mediation have failed, Reuters reported, quoted by BTA.
The US-backed Kurdish militias blamed the "approach taken by Ankara" and its refusal to "accept key points".
According to a representative of the Syrian opposition, Turkey is not happy with the interim ceasefire agreement aimed at ensuring the safety of civilians and wants to continue to exert maximum pressure on the Kurdish militias.
Last week, Turkey announced that its so-called The Syrian National Army has established full control over Manbij.
The new head of the UN Office for the Coordination of Humanitarian Affairs, Tom Fletcher, meanwhile, called for a "massive flow of aid" to Syria, Agence France-Presse reported.
"The situation (in the country) is extremely dramatic," Fletcher told journalists in Damascus and called for the acceleration of humanitarian supplies.