“The factories laid us off because we have no work permits,” Ahmed Atalai, 24, said as he waited with a group to cross the border into Syria. He left Istanbul, but after a month looking for work in southern Turkey where he was registered, was leaving the country. “There’s no work.”

Mayor Fatma Sahin, a senior official in Mr. Erdogan’s party, has been a strong supporter of Syrian refugees for the economic boost they have brought the city but says they have to obey Turkey’s laws.

“What we say to the Syrians is there are rules to live here, so you have to obey those rules,” she said.

But Syrians see the new policies are aimed at making them leave. “They need to make us think it is better to go back to the safe zone,” said Abdulkarim Alrahmon, who runs a branch of a well-known Syrian perfumery in Gaziantep.

The vans and buses of Syrian refugees arrive almost hourly at the border crossing near the town of Kilis, adjoining a Turkish-controlled area of northwestern Syria. Syrians living nearby said the police were depositing unregistered refugees directly across the border.

The Syrians being deported represent only a fraction of the Syrian refugees in Turkey. But the deportations send a sharp message to Mr. Erdogan’s political opponents that he is taking action to reduce the number of refugees, and signal to Europe and the United States that he needs a new solution.

In Gaziantep, Mayor Sahin said she supported the plan for a safe zone in Syria and expected that half of the 500,000 Syrian refugees in her province would move there.