Iran has released British-Iranian aid worker Nazanin Zaghari-Ratcliffe from house arrest, her lawyer Hojjat Kermani told Iranian website Emtedad on Sunday, after her five-year prison sentence for plotting to overthrow the clerical establishment.

"She was pardoned by Iran's Supreme Leader last year, but spent the last year of her term under house arrest with electronic shackles tied to her feet. Now they're cast off," Kermani told the website. "She has been freed."

It was not immediately clear whether she was allowed to leave Iran. Kermani was quoted as saying that "a hearing for Zaghari's second case has been scheduled at branch 15 of the Revolutionary Court of Tehran" according to the website.

Nazanin's husband Richard Ratcliffe told Iran International that "The game of leverage continues. She is very happy to have the ankle tag off - and to be able to visit her granny’s and see the city. So is enjoying today and not thinking about what next Sunday might bring."

Britain said Sunday the continued confinement of British-Iranian aid worker Nazanin Zaghari-Ratcliffe was "unacceptable" and that she must be released so she can return to her family.

"We welcome the removal of Nazanin Zaghari-Ratcliffe’s ankle tag, but Iran continues to put her and her family through a cruel and an intolerable ordeal," foreign minister Dominic Raab said in a statement.

Ratcliffe has said that his wife is a “diplomatic hostage” for Iran which has arrested many foreigners before as a means of pressure on Western countries. One complicating factor is a 400-million-pound debt the United Kingdom has to Iran for weapons ordered and paid for before the 1979 revolution by Iran’s monarchy. A decade ago, the international court of justice ruled that Britain must pay Iran the 400 million pound, but sanctions have prevented payment.

"She must be released permanently so she can return to her family in the UK. We will continue to do all we can to achieve this. We have relayed to the Iranian authorities in the strongest possible terms that her continued confinement is unacceptable." 

British lawmaker Tulip Siddiq said on Sunday she had spoken to the family of Zaghari-Ratcliffe and that they told her she had had her ankle tag removed, but has been summoned again to court.

"I have been in touch with Nazanin's family. Some news: 1) Thankfully her ankle tag has been removed. Her first trip will be to see her grandmother. 2) Less positive - she has been summoned once again to court next Sunday," Siddiq, who is the member of parliament for where Zaghari-Ratcliffe used to live, said on Twitter.

Zaghari-Ratcliffe, a project manager with the Thomson Reuters Foundation, was arrested at a Tehran airport in April 2016 as she prepared to head back to Britain with her daughter after a family visit.

She was later sentenced to five years in jail after being convicted of plotting to overthrow Iran's clerical establishment. Her family and the foundation, a charity that operates independently of media firm Thomson Reuters and its news subsidiary Reuters, deny the charge.

Like other similar cases of plots against national security made against foreigners, the charges were vague, and the trial was not conducted according to international standards and due process of law.

She was released from jail in March last year and put under house arrest in Tehran in response to concerns about the spread of COVID-19 in Iran's prisons, but her movements were restricted and she was barred from leaving the country. 

Reporting by Reuters