Britain's Foreign Office said on Friday it was "very concerned" by reports from Iran that local embassy staff may face trial in connection with demonstrations against last month's presidential election, Reuters reported.
"We are very concerned by these reports and are investigating," a spokeswoman said. "Allegations that our staff are involved in fomenting unrest are wholly without foundation. We will be seeking an urgent explanation from the Iranians."
She said British authorities were speaking to the Iranian embassy in London and to Iranian officials in Tehran.
Two local employees of the embassy are being held by the Iranian authorities, accused of inciting violence during demonstrations against the election results.