A British-Iranian woman being held in an Iranian prison has been released from solitary confinement, her husband has said.

Nazanin Zaghari-Ratcliffe, 37, was sentenced in September to five years in prison on secret charges related to a “soft overthrow” of the country’s government that were not revealed in open court.

She had been restricted from any contact with fellow inmates at Tehran’s Evin prison until a week ago, when she was moved to a general ward, Richard Ratcliffe, her husband, told the BBC.

However, Ratcliffe also criticised the lack of action from the British government, which has never publicly called for his wife to be released. Insisting his wife is innocent, he accused officials of allowing his family to be “caught up as a bargaining chip in international politics”.

Ratcliffe told the BBC Radio 4’s Today programme that his wife was released from solitary confinement for the first time over the Christmas period and was now being held with about 30 other women.

She had been on hunger strike and had suicidal thoughts, he said, but the move had lifted her spirits. “She’s still sad and very low but there’s more fight in her again. I think having been moved so that she’s with other women makes a big difference,” Ratcliffe said.

Zaghari-Ratcliffe was arrested at Imam Khomeini airport on 3 April as she was trying to return to Britain after a holiday visiting family with her two-year-old daughter, Gabriella. The toddler is being looked after by her grandparents in Tehran.

Ratcliffe had originally kept silent about the plight of his wife and daughter, but eventually went public in an effort to put pressure on Iranian authorities – a move he credits with helping improve her situation. But he said he had been left “pretty cross” by the apparent lack of effort made by Britain to secure her release.

“I think they certainly could have stood up for Nazanin a bit more. They have never publicly called for her release, they never criticised her treatment,” Ratcliffe said. He has previously said he believes an unpaid £500m debt relating to an arms deal dating back to Iran’s pre-revolutionary era may be a motive behind Iran’s actions.

“And I would stand by that,” he said. “It’s exactly what it’s about and obviously then our family being caught up as a bargaining chip in international politics is a pretty tough place to be.”

Ratcliffe said he expected his wife’s appeal to be heard on Wednesday, and hoped the new hearing would reveal some detail of the charges she faced. In the meantime, he is trying to get a visa to enter the country and visit his daughter, who celebrated her second birthday in June without her mother or father.