Iranian President Hassan Rouhani on Wednesday began the second leg of his European tour seeking assurances over the 2015 nuclear deal, a trip clouded by the arrest of a Tehran diplomat over an alleged bomb plot against opposition exiles in Paris.
Hoping to boost economic cooperation to help offset the return of US sanctions following Washington's pullout from the historic deal, Rouhani arrived late Tuesday in Vienna -- the city where it was signed.
US President Donald Trump unilaterally pulled out of the agreement nearly two months ago, to the ire of the other signatories -- China, France, Germany, Britain and Russia -- which along with the European Union have continued to back the accord.
Austria just took up the European Union's six-month rotating presidency, while Vienna is the home of the UN nuclear watchdog, the IAEA, which monitors Iran's compliance with the accord.
New US sanctions against Tehran will encompass businesses from third countries that continue to operate in Iran.
A number of foreign firms have already announced they would cease their Iranian activities in light of the looming imposition of sanctions.
Iranians had already complained that the hoped-for uptick in foreign investment after the deal had not materialised.
Rouhani's European trip will be of "prime importance" as it could "provide a more precise picture of cooperation between Iran and Europe," Iranian foreign ministry spokesman said at the weekend.
The Iranian government has itself warned that it will not continue to abide by the nuclear agreement if doing so goes against its economic interests.
Rouhani, a moderate conservative re-elected in 2017, began meeting President Alexander Van der Bellen on Wednesday, and was set to meet Chancellor Sebastian Kurz later in the day.
The nuclear deal has been the cornerstone of Rouhani's policy of greater openness with the West, and the US departure has seen him severely criticised by ultra-conservatives at home.
Iran's supreme leader, Ali Khamenei, has demanded Europe provide a number of economic guarantees in order for Tehran to continue its commitment.
Increasing the pressure on Iran's European partners, he ordered preparations be made to quickly restart nuclear activities in case talks collapse.
Rouhani's visit follows reports of the Iranian diplomat's arrest along with five others over a purported foiled attack on a rally of thousands of Iranian opposition supporters in Paris.
Rouhani has not changed his programme over what his foreign minister dismissed as a "false flag ploy" designed as a distraction.
"How convenient: Just as we embark on a presidential visit to Europe, an alleged Iranian operation and its 'plotters' arrested," Mohammad Javad Zarif tweeted.
Just hours before welcoming Rouhani to Austria, Vienna summoned Iran's ambassador and announced that the unnamed diplomat's status would be withdrawn.
The diplomat attached to the Iranian embassy in Austria, who was detained in Germany, was believed to be a contact of a couple at the centre of the alleged plot.
He may soon be extradited to Belgium, which is spearheading a probe into the alleged bomb plot, prosecutors told the German news agency DPA.
Zarif, who is accompanying Rouhani, will on Friday meet top envoys from the five powers for the first time since Washington's withdrawal.
Kurz meanwhile said he would speak plainly with Rouhani about Iran's role in the Middle East, as Tehran continues to deny accusations it is destabilising the region.
Kurz will also find "clear words" to discuss the human rights situation in Iran, the chancellor told Austrian news agency APA.