Al Jazeera's Jonah Hull in London, quoting British embassy officials in Tehran, said the arrests had taken place over the course of the last two weeks.

"This is a sort of running total - if you like - of a number of arrests and detentions of British embassy employees believed to be local Iranians rather than British citizens," he said.

Which is even more upsetting, in a way. I imagine/hope it's been kept quiet up to now because diplomatic measures were being tried first. But it's horrible to think of people being picked off one by one. If any remaining local staff and their families want a plane ticket and a visa (if that's enough), I really hope we're seeing to that.