THE sister-in-law of a jailed British-Iranian woman has claimed she is being held because of an outstanding arms debt between the UK and Iran.

Cwmbran GP Rebecca Ratcliffe says she believes Nazanin Zaghari-Ratcliffe, who is currently behind bars in Iran for allegedly plotting to topple the government in Tehran, is being used as a “bargaining chip”.

But the Foreign Office has rejected the claim, saying it is doing all it can to help the charity worker and her family.

The mother from Hampstead, north-west London, was originally arrested at Tehran Airport on April 3 along with her then 22-month-old daughter, Gabriella.

She was sentenced to five years in prison in September following a conviction on unspecified “national security-related” offences, following a trial before a revolutionary court in the capital Tehran.

Dr Ratcliffe’s brother, Richard, who is married to Mrs Zaghari-Ratcliffe, said claims by Iran that his wife is a spy “are political code for a ‘bargaining chip with Britain’ – a signal that the British government should understand”.

He said his family has been “caught up” in a disagreement between the two countries, claiming the UK owes about £500 million for a tank deal 40 years ago.

He said: “There is a link as to why Nazanin is still being held and the UK government’s reluctance to pay its debts. My family are caught as collateral.”

On Friday, Mrs Zaghari-Ratcliffe’s family announced she had ended a five-day hunger strike amid fears they had for her health.

Dr Ratcliffe added: “Behind all of it, there is a family being torn apart by politics.”

The issue of Mrs Zaghari-Ratcliffe’s continued detention is expected to be raised at Prime Minister’s Questions tomorrow.

A foreign office spokesman said: “The prime minister and foreign secretary have both raised her case with their counterparts in Iran and will continue to do so.

“We have been supporting her family since we were first made aware of her arrest and the minister for the Middle East, Tobias Ellwood, has met the family to reassure them that we will continue to do all we can.

“While we continue to press the Iranians for consular access and for due process to be followed, we also stand ready to help get her daughter back safely to the UK if requested.”

The family are currently involved in a Write for Rights campaign, through Amnesty International, to have their pair released.

For information, search, Write for Rights Nazanin Zaghari-Ratcliffe appeal.