Syrian authorities, battling a rebel uprising in which 80,000 people have been killed, on Sunday advised citizens against travel to neighboring Turkey on safety grounds.
Tens of thousands of Turkish protesters have rallied for three days against Prime Minister Tayyip Ergodan's government, to the barely disguised delight of Syria's government which blames Erdogan for fuelling Syria's civil war.
Syria's Foreign Ministry said it advised Syrians "against travel to Turkey for the time being for their own safety, because of the deteriorating security situation in several Turkish cities...and the violence of Erdogan's government against peaceful protesters".
Erdogan, a former ally of Bashar al-Assad, turned against him after the Syrian president sought to crush largely peaceful protests which broke out in March 2011 and have since descended into a brutal civil war.
Turkey is hosting 370,000 refugees who have fled Syria's bloodshed. It has also been a base for Assad's military and political foes, as well as a transit point for weapon supplies flowing into northern Syria.
On Saturday Syria called on Erdogan to halt what it called his violent repression of protests or step aside - a direct echo of the appeals to Assad in the early days of Syria's uprising.
"The demands of the Turkish people don't deserve all this violence," Information Minister Omran Zoabi said. "If Erdogan is unable to pursue non-violent means, he should resign."