- France has told its diplomats and foreign ministry officials to postpone indefinitely all non-essential travel to Iran, citing a foiled bomb plot and a hardening of Tehran’s attitude towards France, according to an internal memo seen by Reuters.

Any hardening of relations with France could have wider implications for Iran. France has been one of the strongest advocates of salvaging a 2015 nuclear deal between Iran and world powers, which U.S. President Donald Trump pulled out of in May.

Iran’s economy has been hammered by the prospect of the re-imposition of U.S. sanctions that had been lifted under the deal. European countries including France have pledged to try to soften the economic blow, but have been unable so far to persuade their firms to defy Washington and stay in Iran.

French oil and gas major Total and its carmakers PSA and Renault have led an exodus of European companies from Iran, fearful of the extra-territorial reach of Washington’s sanctions.

“The behavior of the Iranian authorities suggests a hardening of their position vis-a-vis our country, as well as some of our allies,” Maurice Gourdault-Montagne, the ministry’s secretary general wrote in the notice dated Aug. 20.

“Given the known security risks ... all departmental officers, whether from headquarters or (overseas) posts, are required to defer until further notice, except for urgent work, any travel plans in Iran,” Gourdault-Montagne added.

The instructions were also relayed to officials in government departments outside the foreign ministry to be passed on to staff who intended to travel to Iran, a separate memo obtained by Reuters showed.

France’s latest travel advisory for its citizens, published on May 10, cautions against visitors entering Iran with electronic equipment such as drones and walkie-talkies and taking too many photographs.

Iran has said it had nothing to do with the alleged plot to attack a National Council of Resistance of Iran (NCRI) meeting on June 30. Germany has detained an Iranian diplomat based in Austria. Belgium, where the plot was uncovered, has sought the diplomat’s extradition.

French officials have not commented on the matter but diplomatic sources have said privately that if Iran’s involvement were proven then it would be difficult for France not to react strongly.