DUBAI (Reuters) - Iran said on Tuesday it had arrested a dual national last week in Tehran linked to Britain’s intelligence service, the latest in a string of arrests of dual nationals over the past year.

“The accused was working in an economic sector related to Iran,” Tehran prosecutor general Abbas Jafari Dolatabadi was quoted as saying by the state news agency IRNA.

Dolatabadi did not identify the accused person or the second nationality.

Britain said it was trying to find out more about the arrest.

“We are seeking information following the reported detention of a dual Iranian-British national in Iran,” the Foreign Office said in a statement.

The Iranian prosecutor said the arrest was part of a crackdown against what officials have portrayed as “Western infiltration”.

Iran’s potential opening up to the West after last year’s nuclear deal has alarmed Iranian hardliners.

Iran’s Revolutionary Guards have arrested at least six other dual-nationality citizens, or expatriates, upon their return to visit Iran in the last year, the highest number of Iranians with dual-nationality detained in recent years to have been acknowledged.

The government has confirmed most of the detentions, without giving details of any charges.

The government does not recognize dual nationality, which prevents relevant Western embassies seeing individuals who have been detained.

In a telephone conversation last week, British Prime Minister Theresa May raised concerns with Iranian President Hassan Rouhani over the detention of some dual British-Iranian nationals.