A United Nations group has called on Iran to immediately release a British-Iranian mother and former Brockley resident jailed for allegedly plotting to topple the Tehran government.

Charity worker Nazanin Zaghari-Ratcliffe, who lived in Tywhitt Road, was apparently jailed for five years in September, but the UK authorities have not been given details of the sentence or the charges.

The UN Working Group on Arbitrary Detention (WGAD), in response to a claim by charity Redress, found that her imprisonment and separation from her two-year-old daughter, who is in the care of her Iranian grandparents, was in breach of the international covenant on civil and political rights.

The WGAD has requested Iran to "take the necessary steps to remedy the situation of Ms Ratcliffe without delay".

It said: "Taking into account all the circumstances of the case, especially the risk of harm to Ms Ratcliffe's health and physical integrity and to the well-being of her child, the Working Group considers that the adequate remedy would be to release Ms Ratcliffe immediately, and to accord her an enforceable right to compensation in accordance with article 9(5) of the ICCPR."

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It further urged Iran to fully investigate the circumstances surrounding Mrs Zaghari-Ratcliffe's deprivation of liberty and to take appropriate measures against those responsible for the violation of her rights.

In addition, it referred the case to the UN Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment.

The group said it "considers that there is an emerging pattern involving the arbitrary deprivation of liberty of dual nationals in Iran".

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Richard Ratcliffe, Mrs Zaghari-Ratcliffe's husband, said: "I am grateful that the UN has taken such a strong stand. Last week five UN Special Rapporteurs described Nazanin's case as a 'mockery of justice'.

"Now the UN Working Group has called for her to be released, and compensated. The morality of our situation is clear.

"It is time for the UK government to follow their lead."

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He continued: "Whatever other priorities the UK government has in its dealings with Iran, it should be clear that this is nonsense.

"It is not acceptable for a British citizen to be treated in this way, or for a British two-year-old to be so arbitrarily separated from her parents.

"Six months passed cannot be recovered. The government needs to ensure this ends soon."

Mrs Zaghari-Ratcliffe, 37, was arrested at Imam Khomeini airport on April 3 as she was trying to return to Britain after a holiday visiting family with her daughter Gabriella.