LONDON, ENGLAND - Britain is pressing Iran's Foreign Ministry to help secure the release of four local employees of the British embassy who are being held by Iranian authorities, Foreign Secretary David Miliband said on Tuesday.

Iranian authorities detained nine Iranian employees of the British embassy, accusing them of stirring street protests that rocked Iran after a disputed June 12 presidential election. Britain rejects the accusation.

Five of the staff were released but four are still being held.

'We are extremely concerned at the continued detention of some of our locally engaged staff in Tehran. This is unacceptable harassment and intimidation...,' Miliband told parliament, calling for their release.

He said he and Iranian Foreign Minister Manouchehr Mottaki had agreed in a telephone conversation on Monday that 'a swift resolution was in both of our interests'.

However, Miliband said: 'It's not the Ministry of Foreign Affairs in Tehran who goes around arresting people.'

'I made very clear, and Mr Mottaki understood and responded to this, that we did expect the Ministry of Foreign Affairs to engage actively in securing the release of the remaining staff ... And that's certainly what's going on at the moment.'

EU WARNING

The European Union said on Sunday it would meet any Iranian intimidation of European diplomatic staff with a 'strong and collective response'.

Official results showed President Mahmoud Ahmadinejad won the election by a landslide, sparking days of street protests by supporters of his main moderate challenger, former prime minister Mirhossein Mousavi, who said the vote was rigged.

State media say about 20 people were killed.

Iran has accused Britain and the United States of interfering in its internal affairs and fomenting post-election unrest. London and Washington have denied the allegations.

Britain and Iran have expelled two of each other's diplomats.

Miliband said Britain would work 'intensively' with its partners over the next three weeks to ensure a united international position on dealing with the Iranian government.

Ahmadinejad is due to be sworn in between July 26 and August 19.

He said the European Union would 'need to go further' with sanctions against Iran if Tehran did not accept an international offer of negotiations on its nuclear programme by year-end.

Britain and other Western countries suspect Iran of seeking to develop nuclear weapons. Iran denies this, saying it only wants a civil nuclear programme to generate electricity.