Starting in the week after the arrest of Soleimanpour, companies have been unable to get letters of credit cleared through the Commerce Ministry, ostensibly because of administrative hitches. However, companies say they were told by Iranian customs officers that no imports from the UK were being allowed through. They also say they have been told by non-official sources close to the government that there is an unofficial and undisclosed embargo against UK and Argentine firms.

The government denies imposing politically-motivated restrictions on trade from the two countries. The UK embassy says companies have reported difficulties in getting imports through, but there has been no official notification of an embargo. It says it is in discussion with Tehran over the reasons behind the difficulties.

Soleimanpour was arrested on an Argentine extradition warrant naming him as responsible for organising and commissioning the 1994 bombing of a Jewish centre in Buenos Aires. Iran says he is still on its diplomatic payroll and therefore eligible for immunity. But the UK says he is not registered as a diplomat in Britain and is subject to the legal process. Soleimanpour was released on bail after a hearing in late September, when a UK judge said Buenos Aires’ case was based mainly on hearsay.