British Embassy staff in Tehran will face trial for their alleged role in the post-election unrest, according to reports in Iran that have "concerned" Downing street. Nine embassy staff were arrested at the weekend as relations between the UK and Iran deteriorated following the disputed re-election of president Mahmoud Ahmadinejad. Prime Minister Gordon Brown's spokesman said clarification is being sought from the Iranian government regarding the claims made by top Iranian cleric Ayatollah Ahmad Jannati. During Friday prayers in Tehran, he said: "In these developments their embassy here maintained a presence in which individuals were arrested and inevitably they will be tried as they have made confessions." Mr Brown's spokesman said: "We are aware of these reports. We are concerned about these reports and we are seeking clarification on this as a matter of urgency." Ayatollah Jannati, head of Iran's powerful Guardian Council, did not say how many of the embassy's Iranian staff would be tried or on what charges. But he claimed that the staff "made confessions". Iranian state media previously claimed that all but one of those arrested at the weekend had been released. They were accused by the Iranian authorities of being involved in anti-government protests.