Nazanin Zaghari-Ratcliffe has said the UK government should be doing more to secure the release of a Scottish man detained for six years in India.
The British Iranian national was arbitrarily arrested in 2016 and detained in Iran for six years.
She said both she and Jagtar Singh Johal, from Dumbarton, should have been better protected by the UK government.
The UK government said it was committed to seeing Mr Johal's case resolved as soon as possible.
Mr Johal, a Sikh activist, was arrested in November 2017 after travelling to India to attend a wedding.
The 36-year-old has been accused of being part of a terror plot and faces eight charges of conspiracy to murder linked to political violence in India.
Mr Johal claims he was tortured in the initial days of his detention - an accusation the Indian authorities have strenuously denied. His trial is under way but he has not been convicted.
Speaking to BBC Scotland News on the sixth anniversary of his detention, Nazanin Zaghari-Ratcliffe said that while the two cases were different in some ways, she believed ministers in London should be doing more for Mr Johal.
"It is not acceptable that the government to date has not called for his release," she said.
"When Prime Minister Rishi Sunak went to India [for the G20 summit] he didn't call for his release and I think that's something the government should do in terms of protecting its citizens beyond its UK borders."
Mr Sunak has previously confirmed that he raised the case of Jagtar Singh Johal in talks with India's prime minister Narendra Modi in September.
Ms Zaghari-Ratcliffe was arrested initially on spying charges which she strongly denied.
She was widely seen as a hostage used by the Iranians to pressure the UK government to pay a long-standing debt, and was released in March last year once a diplomatic settlement was reached.
In her interview, Ms Zaghari-Ratcliffe, spoke of the impact on family members when a person is detained abroad.
"I think my parents and my family, Richard and my daughter, it was harder for them than me and it must be very hard for Jaggi's family and in his case, more so because they know very little about his whereabouts and how he's spending his time."
Jagtar's brother Gurpreet Singh Johal, who is a solicitor and Labour councillor, told BBC News the support of Ms Zaghari-Ratcliffe and her husband Richard meant a lot to him.
"They understand, better than anyone, how painful it is that the UK government has failed to seek Jagtar's release.
"I found Nazanin's comments about how hard it was for her family very moving.
"It doesn't get any easier being separated from my brother, not even being able to talk to him regularly or know what he's going through. We've been lucky to have the community's support."
Last year a UN panel of experts concluded Mr Johal's detention was arbitrary, lacked legal basis and he should be freed immediately.
The Indian government has maintained that due process is being followed and Mr Johal was arrested based on evidence and according to the laws of India.
A Foreign Office spokesperson said: "The UK government is committed to seeing Jagtar Singh Johal's case resolved as soon as possible.
"We continue to provide consular assistance to Mr Johal and his family and have consistently raised his case directly with the government of India."