Germany said Monday it had banned Iranian airline Mahan Air from its airports, in an escalation of sanctions adopted by the European Union against Tehran over attacks on opponents in the bloc.
The move was necessary to protect Germany's "foreign and security policy interests", foreign ministry spokesman Christofer Burger told reporters at a regular Berlin press conference.
Officials at the Federal Aviation Office (LBA) sent Tehran-based Mahan Air a notification "ordering the immediate suspension of its authorisation to operate passenger flights from and to Germany" from Monday, a transport ministry spokeswoman added.
Mahan, Iran's second-largest carrier after Iran Air, flies four services a week between Tehran and the German cities of Duesseldorf and Munich.
It was blacklisted by the US in 2011, as Washington said the carrier was providing technical and material support to an elite unit of Iran's Revolutionary Guards known as the Quds Force.
The US treasury has threatened sanctions against countries and companies offering the airline's 31 aircraft landing rights or services such as on-board dining.
But Brussels and Washington have been at odds on how best to deal with Iran since President Donald Trump's decision to withdraw from a 2015 deal lifting some sanctions in exchange for Tehran suspending its nuclear programme.
Foreign ministry spokesman Burger reiterated that Germany wished to "uphold" the agreement "and play our part in keeping economic exchange with Iran possible".
"But we have always said that destabilising activity by Iran in the (Middle East) region as well as Iran's ballistic missile programme are unacceptable," he added.
"On top of that, there are recent indications regarding the activities of Iran's secret services within EU states."
The EU earlier this month targeted sanctions at Iran's security services and two of their leaders, accused of involvement in a series of murders and planned attacks against Tehran critics in the Netherlands, Denmark and France.
Brussels' measures included freezing funds and financial assets belonging to Iran's intelligence ministry and individual officials, but did not target any companies.
US Ambassador to Germany Richard Grenell, a close Trump ally, welcomed Berlin's decision.
"Mahan Air has flown terrorists, weapons, equipment, and funds to international locations to support Iranian terrorist proxy groups," he said in a statement, adding that it had been used "to support the Assad regime in Syria."
Since his arrival, Grenell has exerted unusually intense pressure on German firms over Iran sanctions.
Rail operator Deutsche Bahn, Deutsche Telekom, Mercedes-Benz parent Daimler and industrial group Siemens have all said they will stop their operations in the country. Last week German authorities said they had arrested a German-Afghan military advisor on suspicion of spying for Iran.