Iran says Britain has been stoking unrest since the elections
Three more Iranian British embassy staff have been released by the authorities in Tehran, Iran's state-run Press TV reports.
Nine embassy employees were detained at the weekend and Press TV said all but one had now been freed.
However, the UK Foreign Office said two people had been freed and it was seeking confirmation on the third.
Iran said the staff had had a role in protests against the disputed presidential election result.
In a statement, the British Foreign Office said it could confirm that two of its staff had been released over the last two days
"We are also seeking confirmation following Iranian reports that a further member of staff has been released today."
The statement said its top priority was ensuring the release of all staff and that said it was continuing "intensive discussions with the Iranian authorities and our international partners to resolve this issue".
Earlier, UK Prime Minister Gordon Brown had again expressed "deep disappointment" at the Iranian authorities' conduct.
He told a news conference at Downing Street on Wednesday that Iran was trying to blame its post-election protests on Britain.
"This action is unjustified and it is unacceptable and some people in Iran are trying to seek to use Britain as an explanation for the legitimate Iranian voices calling for greater openness and democracy," he said.
The state media's announcement that three more staff had been released comes after five of their colleagues were freed Monday.
Iran's semi-official Fars television station reported that one of the detainees had played a "remarkable role during the recent unrest in managing it behind the scenes".
Britain had strongly protested against the arrests, with Foreign Secretary David Miliband saying they were "completely contrary to the sort of good political engagement that Iran says that it wants".
There was no immediate response from Britain to the latest reports of releases.
Tehran has repeatedly accused foreign powers - especially Britain and the US - of meddling after the election.
Maj Gen Hassan Firouzabadi, Iran's top military officer, said on Wednesday that until Europe apologised for what he called this "huge mistake" it could no longer participate in talks on Iran's controversial nuclear programme.
The BBC's Diplomatic Correspondent, Jonathan Marcus, says the release of the staff will go some way to repairing damaged ties between Iran and the European Union.
But many questions still remain over how the West should deal with Iran in the post-election unrest which left at least 17 people dead, says our correspondent.
EU governments have considered temporarily withdrawing their ambassadors to Iran in protest and will be seeking to ensure the remaining embassy staff member is released.
The problem is that western countries must continue to talk to Iran about its nuclear programme, and Iran would also use any external pressure as proof of interference in its affairs, our correspondent adds.