London - Britain's Foreign Secretary, David Miliband, demanded on Thursday that the authorities in Iran overturn a reported four-year sentence given to an employee at the embassy in Tehran for allegedly fomenting this summer's civil unrest.

Hossein Rassam, 44, was arrested in June at the time of massive street protests over the country's disputed presidential election, and according to The Times newspaper, handed a four year sentence.

Miliband called the reported sentence "wholly unjustified" and said it represented "further harassment of embassy staff for going about their normal and legitimate duties".

In an escalating diplomatic incident, the Iranian ambassador in London has been summoned to the foreign office to explain the sentence, he added, whilst the British ambassador in Tehran has complained to the country's deputy foreign minister.

Mr Miliband said "We understand the sentence can be appealed. I urge the authorities to conduct this quickly and overturn this harsh sentence."

"This will be seen as an attack against the entire diplomatic community in Iran and important principles are at stake."

Rassam worked as a political analyst at the embassy, but Tehran accused him of spying and inciting civil unrest.

It was unclear whether he had already started the sentence, or was free pending a possible appeal.

Seven other embassy employees were arrested at the same time as Rassam, as large street protests against the apparent rigging of the country's presidential election shook Tehran and other cities. (dpa)