A dual nationality British-Iranian has been sentenced to six years in prison in Iran on spying charges, according to authorities.

The dual citizen has not been named and details of the case have not been disclosed, including when the person was arrested or where.

Announcing the ruling on Sunday night, Tehran prosecutor Abbas Jafari-Dolatabadi said only that the courts had handed down a “six-year prison sentence for an agent of England's intelligence service".

The Mizan Iranian news agency quoted him as saying the same British-Iranian citizen was also under investigation in a separate case related to a private bank, giving no further details.

There are two public cases of British-Iranians held in Iran, one of them being Nazanin Zaghari-Ratcliffe, the charity worker accused of plotting the overthrow of Iran's government.

However, there are likely to be more cases, which have not been publicised by either the Iranian authorities or family members of those held in Iran.