France is "extremely worried" about the health of a French-Irish citizen held in Iran, the foreign ministry said Tuesday, as UN rights experts accused Tehran of institutionalised "hostage-taking".
The developments came as an Iranian newspaper said authorities had arrested a German for allegedly photographing oil facilities in the southwestern province of Khuzestan.
Around two dozen foreigners and dual nationals are detained in Iran, as hopes fade of reviving a 2015 deal on the country's nuclear programme and as four months of anti-regime demonstrations rock the Islamic republic.
Paris is "extremely worried" about the poor health of Bernard Phelan which "requires appropriate medical monitoring", the ministry said.
Phelan, a Paris-based travel consultant, 64, was arrested in October and is being held in Mashhad in northeastern Iran, according to Irish media reports.
Ireland said it had "been providing consular assistance, in close coordination with France, since the outset".
His sister, Caroline Masse-Phelan, told AFP he had not been put on trial but was arrested on accusations of spreading anti-regime propaganda.
She said was already on a hunger strike and had started refusing water Monday.
He is one of seven French nationals held arbitrarily in Iran, according to the foreign ministry.
- 'Flagrant violations' -
Also Tuesday, UN rights experts slammed the detention of Belgian aid worker Olivier Vandecasteele, who was arrested in Iran in February 2022.
Vandecasteele, 41, was last week handed multiple sentences totalling 40 years on a range of charges, including "espionage".
But with the sentences to run concurrently, he will serve 12 and a half years in jail, the judiciary's Mizan Online website reported. He was also sentenced to 74 lashes.
"We believe Mr Vandecasteele has been arbitrarily deprived of his liberty and is a victim of enforced disappearance," a group of eight independent experts said.
They warned his "right to a fair trial before an independent and impartial tribunal has been violated", adding: "These are flagrant violations of Iran's obligations under international law."
The experts called on Tehran to "end the institutionalised practice of hostage-taking and to release the many foreign and dual nationals who remain arbitrarily detained."
Tehran does not recognise dual nationality for its citizens, and has insisted all the foreigners held are on the grounds of domestic law.
Supporters of Vandecasteele and rights groups contend he is being held as part of an effort by Tehran to pressure Belgium to release an Iranian diplomat incarcerated for terrorism.
Meanwhile, Iran's Jam-e Jam newspaper said Tuesday authorities had arrested a German national "while taking pictures of oil facilities in Omidiyeh", without providing details on his identity or date of arrest.
Germany said it was aware of the reports and said its ambassador was "currently seeking to shed light on this matter".
- Dual national executed -
A US citizen jailed in Iran, Siamak Namazi, had announced a seven-day hunger strike starting Monday as he implored President Joe Biden to put greater priority on his case.
Namazi, who was arrested in October 2015, launched the hunger strike on the anniversary of the 2016 release of five other Americans as Iran and the United States implemented the landmark nuclear deal brokered by then president Barack Obama.
Obama's successor Donald Trump bolted from the deal but obtained the release of two additional Americans from Iran in prisoner swaps.
The Biden administration sought to restore the nuclear deal and made clear it could not go forward without the release of imprisoned Americans.
But Biden has acknowledged that the deal is effectively dead after painstaking negotiations, and as attention focuses on Iran's deadly crackdown on protests.
Iran has been rocked by demonstrations over the September 16 death in custody of Mahsa Amini, a 22-year-old Iranian Kurd who had been arrested for an alleged breach of the country's dress code for women.
Authorities have made thousands of arrests amid a bloody crackdown that has claimed hundreds of lives, and have executed four people in connection with the unrest.
The protests have further strained ties between Iran and the West, with Tehran accusing some foreign countries of fomenting what it calls "riots".
French-Irish national Phelan was travelling through Mashhad during the protests when he was arrested.
Iran said Saturday it had executed a British-Iranian dual national, Alireza Akbari, for spying for the United Kingdom, sparking international outrage.
The UN experts said they were "appalled by Akbari's execution", pointing out that he was reportedly tortured and "forced to make false confessions".
He had been arrested more than two years earlier.