Britain on Friday extended diplomatic protection to a British-Iranian mother jailed in Tehran in a move that was immediately branded by the Islamic republic as a violation of international law.
The fate of Nazanin Zaghari-Ratcliffe has been a bone of contention between Tehran and London since her arrest in Iran in January 2016.
The 41-year-old was returning from a family visit with her infant daughter when she was detained at Tehran airport.
Her husband Richard said Zaghari-Ratcliffe suffers from a range of health problems and that a lack of medical access in jail forced her to go on a brief hunger strike in protest in January.
"She's been getting very low, partly despairing.. what's the escalation beyond that?" he told AFP.
"I'm really glad that the foreign secretary has made this the escalation... It will make a difference."
Ratcliffe said the move made it clear to Iran that Britain believes his wife has suffered an injustice and that the government will keep up the pressure.
"These are all really important and welcome steps, so we're very happy," he said, adding Zaghari-Ratcliffe would also be "thrilled".
Diplomatic protection is a rarely-used mechanism allowing nations to seek protection on behalf of its citizens on the grounds that they have been wronged by another state.
British Foreign Secretary Jeremy Hunt noted Friday it "hasn't happened for an individual, we don't think, for more than 100 years".
Hunt said he made the decision because he wanted to signal to Iran that Britain had no intention of letting Zaghari-Ratcliffe languish in jail.
"We hope the Iranians will react constructively to this and understand that we are not going to drop this," he told BBC radio.
"At the heart of this is an innocent woman, vulnerable, unwell and scared and she has a four-year-old daughter.
"She should not be paying the price for the disagreements you have with the UK." But Iran quickly branded London's decision a violation of international law.
"UK Govt's extension of diplomatic protection to Ms Zaghari contravenes int'l law. Govts may only exercise such protection for own nationals," Tehran's London envoy Hamid Baeidinejad tweeted late Thursday.
"As UK Govt is acutely aware, Iran does not recognize dual nationality. Irrespective of UK residency, Ms Zaghari thus remains Iranian," he wrote.
Ratcliffe said he had discussed the expected negative reaction from Iran with the Foreign Office, and they hoped the "enough is enough" message would sink in.
"There'll be parts of the Iranian regime that are sympathetic to that, and there'll be parts -- that are holding Nazanin -- who are digging their heels in and may well dig their heels in further," he added.
Zaghari-Ratcliffe was a project manager with the Thomson Reuters Foundation -- the media group's philanthropic arm -- and made frequent visits to Iran.
But she was on a private holiday and not a work assignment at the time of her arrest.
She was sentenced to five years in prison in September 2016 for allegedly trying to topple the Iranian government.
The Thomson Reuters Foundation and the British government have consistently denied the charges against her.
Ratcliffe told reporters in January that Iranian authorities were trying to make his wife spy on the British government for them once she is released from jail, but she had refused.
He has also been highly critical of Tehran for denying her requested medical attention after he says she suffered panic attacks and other health issues.
Ratcliffe said Friday he hoped the diplomatic decision would mean British officials could now visit her for the first time, and allow for access to an independent doctor to "check just how ill she is".
"Now it is effectively a British government case," he told the BBC. "All the injustices that have been done to Nazanin are effectively injustices to the British government.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)