Five out of the nine detained Iranian staff at the British embassy in Tehran have been released, Iran's English-language satellite channel Press TV reported Monday morning.
Iranian media reported Sunday that eight local staff at the British embassy had been detained for their "considerable role" in post-election riots, but Monday's reports said the number should be nine.
British Foreign Secretary David Miliband later on Sunday called the arrests "harassment" and demanded their immediate release.
"The idea that the British embassy is somehow behind the demonstrations and protests that have been taking place in Tehran in recent weeks is wholly without foundation," Miliband said on the sidelines of a European security meeting in Greece.
Relations between Britain and Iran are strained after Tehran accused Britain of stoking unrest, which London denies.
Iran has repeatedly accused foreign powers -- especially Britain and the United States -- of stoking the unrest that swept the country after June 12 election, which handed President Mahmoud Ahmadinejad a decisive victory.
Last week, Iran's Foreign Minister Manouchehr Mottaki warned the country may downgrade its ties with Britain after the two governments expelled each other's diplomats in a tit-for-tat move.
Iran has also expelled a BBC's correspondent in Tehran and arrested a British-Greek journalist, as well as a number of other British passport-holders it said were involved in riot.