ISTANBUL — Border tensions caused by Syria’s civil war worsened on Thursday, as Turkey threatened to prosecute or deport 130 refugees implicated in a violent protest, and Israel reported rising numbers of injured Syrians seeking medical help on the Israeli side of their disputed boundary.

The tensions, which underscored how the Syrian conflict is threatening the region’s stability, came as international diplomacy aimed at ending the conflict faced new complications. Russia, a major supporter of the Syrian government, suggested that the special Syria envoy of the Arab League and United Nations had lost credibility because the Arab League had sided with the insurgency.

Turkey, like Iraq, Jordan and Lebanon, has accepted tens of thousands of Syrian refugees since the uprising against President Bashar al-Assad began two years ago. The Turks threatened for the first time to deport a group of refugees after a riot at one of Turkey’s 17 refugee camps on Wednesday, a threat that alarmed the United Nations refugee agency, which said such a move would violate international law.

Melissa Fleming, a spokeswoman for the United Nations High Commissioner for Refugees in Geneva, said in an interview that a forced return would breach legal protections that prohibit host countries from forcing refugees out.