Members of Bulgarian nationalist groups patrolled Sofia, Bulgaria’s capital, last month, an example of “civil patrols” by nationalists in immigrant regions.

The Bulgarian interior ministry said on Monday that prosecutors have charged three Syrians with attempting to join ISIS militant group after border patrols arrested them as they tried to enter Turkey from Bulgaria.

The three Syrians, having refugee status from Germany, had already failed in attempting to enter Turkey through Greece earlier this year, according to the ministry.

“During operational activities their affiliation to Islamic State has been established, as well as their intention to join the terrorist group,” the ministry said in a statement.

The three men, who had already been given six-month suspended sentences for attempting to cross the Bulgarian-Turkish border illegally might now face up to 10 years in jail if convicted.

Bulgaria, which lies across one of the routes of migrants and refugees inflow to Western Europe, has requested Brussels to close all its external borders until it comes up with a joint solution to the migrant crisis.

Also, Turkish authorities detained on Sunday 97 Syrian refugees, including 22 children, in the trailer of a truck near the border with Bulgaria. The migrants were caught when they attempted to illegally cross the Kapikule-Kapitan Andreevo border checkpoint.