Iran's defeated presidential election candidate Mirhossein Mousavi has called on his supporters
to continue protests but show restraint, his website reported.
"In your protests continue to show restraint. I am expecting armed forces to avoid irreversible damage," Mr Mousavi said in a statement.
Protesting against lies and fraud (in the election) is your (Iranians) right. Today the country mourns for those killed in the protests. I call on you to remain calm."
Iranian authorities earlier blamed "terrorists" for clashes in which at least 10 people were killed and President Mahmoud Ahmadinejad told the United States and Britain to stay out of unrest sparked by his disputed re-election.
Iran state television said 10 people were killed and more than 100 others injured in protests held in Tehran yesterday in defiance of a stern warning by Supreme Leader Ayatollah Ali Khamenei. A separate report put the number of deaths at 13.
State television said the violence included the torching of a mosque, which it blamed on "rioters".
"In the unrest leading to clashes 10 people were killed and more than 100 wounded," it said. "The presence of terrorists ... in yesterday's event in Enghelab and Azadi avenues was tangible."
The harshness of the language suggested the authorities could be preparing for a crackdown to end more than a week of protests.
The disputed June 12th election handed an overwhelming victory to the hardline, anti-Western Mr Ahmadinejad sparking the biggest protests and most violent unrest since the 1979 Islamic Revolution which ousted the US-backed shah.
Opposition leader Mirhossein Mousavi, who came second to Mr Ahmadinejad in the poll and whose followers have spearheaded protests, says the election was rigged and must be annulled.
State television, appealing for Iranian unity, suggested that only the West stood to gain from the unrest and Mr Ahmadinejad accused Washington and London of interfering in Iran's affairs.
"Definitely by hasty remarks you will not be placed in the circle of friendship with the Iranian nation. Therefore I advise you to correct your interfering stances," Mr Ahmadinejad was quoted by ISNA news agency as saying at a meeting with clerics and scholars.
Mr Ahmadinejad was directing this remark at US president Barack Obama and British prime minister Gordon Brown, ISNA said.
Mr Obama, in the forefront of diplomatic efforts to halt an Iranian nuclear programme the West fears could yield atomic weapons, urged Tehran yesterday to "stop all violent and unjust actions against its own people".
"The Iranian government must understand that the world is watching. We mourn each and every innocent life that is lost," Mr Obama said in a statement.
British foreign secretary David Miliband rejected the charge of interference. "The UK is categorical that it is for the Iranian people to choose their government," he said in a statement.
In Paris, European Central Bank President Jean-Claude Trichet said tensions in Iran had added to risks facing the world economy and underlined the need for strengthening the global financial system.
"Any additional geo-strategic tension is obviously an extra risk for the international economy," he told Europe 1 radio.
"We have to live with these risks and reinforce the solidity of the international economy, reinforce the solidity of international finance ...," he said.
There were no immediate reports of street protests today. Government restrictions prevent correspondents working for foreign media from attending demonstrations to report.
State TV earlier announced the arrests of members of the Mujahideen Khalq Organisation (MKO), an exiled opposition group which it accused of "terrorist activities" including setting buses on fire and destroying public property.
Riot police were deployed in force yesterday, firing teargas and using batons and water cannon to disperse groups of several hundred Iranians who had gathered across the city.
Mr Mousavi yesterday said the Islamic Republic must be purged of "lies and deviations" and told supporters he was "ready for martyrdom", according to an ally. But he said he did not seek confrontation with the authorities.
"We are not against the Islamic system and its laws but against lies and deviations and just want to reform it," he said in a statement on his website.
He said if authorities refused to allow peaceful protests they would face the "consequences" - an apparent rejoinder to Khamenei's warning that opposition leaders would be held responsible for any bloodshed resulting from protests.
The authorities reject charges of election fraud.
But the highest legislative body said it was ready to recount a random 10 per cent of the votes cast in the election to meet the complaints of Mousavi and two other candidates.
Reuters