Germany and the European Union on Tuesday strongly condemned Iran's execution of a 69-year-old German-Iranian dissident after years behind bars and warned they were considering retaliatory measures.

Chancellor Olaf Scholz called Jamshid Sharmahd's execution on Monday a "scandal" and Foreign Minister Annalena Baerbock warned Iran's "inhumane regime" of "serious consequences".

Iran's Foreign Minister Abbas Araghchi doubled down and poured scorn on her comments, writing on X that "a German passport does not provide impunity to anyone, let alone a terrorist criminal".

Berlin summoned Iran's charge d'affaires to "convey its strong protest" at the execution. The German ambassador in Tehran also protested to the Iranian foreign ministry and was then recalled to Berlin for consultations.

Berlin "reserved the right to take further measures", the foreign ministry said.

The EU's top diplomat Josep Borrell said the bloc condemned Sharmahd's "killing in the strongest possible terms" and was also "considering measures in response".

A European Commission spokeswoman told reporters that "any measures" could be taken against Iran and that they "have to be discussed with all member states".

Sharmahd, a German citizen of Iranian descent and a US resident, was a software engineer who had worked and written for an Iranian opposition group's website based abroad that strongly criticised the Islamic republic's leadership.

He was seized by Iranian authorities in 2020 while travelling through the United Arab Emirates, according to his family.

Iran accused him of having played a role in a deadly 2008 mosque bombing. He was sentenced to death in February 2023 for the capital offence of "corruption on Earth".

The Iranian judiciary's Mizan website said on Monday that "the death sentence of Jamshid Sharmahd... was carried out this morning".

His family have always vehemently protested his innocence.

Sharmahd's daughter Gazelle said on X she was waiting for the German and US governments to provide "concrete proof" that her father had been killed.

If so, she said, his body should be brought home "immediately" and the Iranian government should face "severe punishment".

A German foreign ministry source said that Baerbock had spoken to Gazelle Sharmahd on Monday "and expressed condolences on behalf of the German government". (AFP)