Germany’s government on Thursday urged its citizens to leave Iran or risk arbitrary arrest and long prison terms there, warning that dual nationals were particularly at risk.

Berlin has welcomed European Union sanctions on Iran, which has unleashed a bloody crackdown on some of the biggest protests in the Islamic Republic since the 1979 revolution.

“German nationals are asked to leave Iran,” a foreign ministry statement said.

“For German nationals there is a concrete risk of being arbitrarily arrested, interrogated and sentenced to long prison terms. Above all, dual nationals who have Iranian as well as German citizenship are at risk.”