British Foreign Secretary Boris Johnson told the British parliament on Monday that his meetings in Tehran were “worthwhile”.

According to Reuters, he said that he urged Iran to release detained dual nationals.

“I urged their release, on humanitarian grounds, where there is cause to do so,” he said.

“These are complex cases involving individuals considered by Iran to be their own citizens, and I do not wish to raise false hopes. But my meetings in Tehran were worthwhile,” he said. “It is too early to be confident about the outcome.”

The spat between London and Tehran over Nazanin Zaghari, a British-Iranian woman, has been on since her detention in April 2016 when she was arrested with her two-year-old daughter at Tehran’s Imam Khomeini International Airport for security reasons while she was about to return to the UK.

Zaghari, previously a project assistant at the BBC’s Media Action who worked for the Thomson Reuters Foundation until her arrest, was sentenced to five years in jail in September 2016, a conviction upheld in the January appeals court.  

While Zaghari is imprisoned at Evin jail, her daughter Gabriella, now three, has been placed in the care of her Iranian grandparents and is allowed to see her mother twice a week.

The Iranian Foreign Ministry said on Monday that it will follow up on the case of Zaghari for “humanitarian reasons”, but emphasized that the Iranian Judiciary acts as an independent body and is the ultimate decision-maker on the issue.

Initial details after Zaghari’s arrest cited implication in post-election unrests in Tehran and some other cities in 2009.