The European Union’s coordinator of the nuclear talks was briefly detained with colleagues at Frankfurt Airport as he was returning to Brussels from Tehran after two days of talks.

Enrique Mora said in a tweet on Friday that “not a single explanation” was given to him, adding that they airport police also took his passport and phones.

The Spanish diplomat criticized the breach of diplomatic rules, emphasizing that he is “an EU official on an official mission holding a Spanish diplomatic passport”.

About an hour later, he said on twitter that he was released. “Now released along with my two colleagues, the EU ambassador to UN Vienna and the head of the EEAS (the European External Action Service) Iran task force”.

Mora added that they “were kept separated” during the short detention and denounced “the refusal to give any explanation for what seems a violation of the Vienna Convention”.

Moreover, Mora said, “While still waiting for continuing my trip to Brussels I want to underline that in Tehran I raised the need to stop execution of Ahmadreza Djalali and asked for his release on humanitarian grounds”.

His comment about Djalali was among the few bits of information that was announced by any official about the content of his meetings in his two-day trip to Iran.