Turkey said Wednesday that it was not satisfied with the buffer zone solutions offered by the United States in northern Syria, aimed at preventing clashes between Turkish and Kurdish forces.
"The latest US proposals are not satisfactory," Foreign Minister Mevlut Cavusoglu told the state-run Anadolu news agency.
"We should say things clearly: we have the impression that (the United States) is trying to buy time," he added.
"A deal must be reached quickly on a security zone. Our patience has run out."
The two countries began talks on Tuesday after Turkey repeatedly threatened to launch an offensive against Kurdish forces in Syria. The buffer zone idea was first mooted by US President Donald Trump in January.
The US has provided extensive support to the Syrian Kurdish YPG militia in Syria.
The YPG has led the fighting against the Islamic State (IS) group in Syria, but Ankara sees it as a terrorist off-shoot of Kurdish militants inside Turkey.
Turkey has launched two previous offensives into Syria against IS and the YPG, in 2016 and 2018 respectively.