International Tensions Increase as 8 UK Embassy Staff Members Detained in Iran
Iranian media earlier reported that eight local staff at the mission had been detained for their "considerable role" in post-election riots.
UK Foreign Secretary David Miliband called the arrests "harassment" and dismissed the allegations as baseless.
Relations between the countries are strained after Tehran accused the UK of stoking unrest, which London denies.
Iran has repeatedly accused foreign powers - especially Britain and the US - of stoking the unrest that swept the country after the 12 June election, which handed President Mahmoud Ahmadinejad a decisive victory.
In the fallout of the crisis, Tehran expelled two British diplomats in the past week, and the UK has responded with a similar measure.