Defeated Iranian presidential candidate Mir-Hossein Mousavi has renewed his call for a rerun of last week's election that returned Mahmoud Ahmadinejad to power.
The 67-year-old former premier, who has lodged a formal complaint over what he says was a rigged election, has promised to continue with his campaign with peaceful rallies.
Leading pro-reform cleric Grand Ayatollah Abdolkarim Mousavi Ardabili has also called on the authorities to look quickly into complaints over the disputed election in order to allay concerns.
Mr Mousavi, who had claimed victory soon after polls closed on Friday, said the vote was marred by 'blatant irregularities.'
He has appealed for peaceful protests or gatherings in mosques tomorrow to mourn those killed during protests this week.
'I ask the people to express their solidarity with the families...by coming together in mosques or taking part in peaceful demonstrations,' Mr Mousavi said on his website.
After Mousavi's message, tens of thousands of his supporters gathered in Tehran's Haft-e Tir Square for a fifth day of demonstrations.
Wearing green wristbands and headbands in the colour of Mr Mousavi's campaign, the demonstrators carried placards accusing President Ahmadinejad of having 'stolen' their votes.
Iranian state television broadcast brief footage of the rally.
Grappling with the biggest wave of public anger since the 1979 Islamic revolution, the government has lashed out at enemy 'plots', hauling in foreign ambassadors, rounding up scores of reformists and clamping down on the media.
World governments have voiced increasing alarm about the situation in Iran, but US President Barack Obama, while raising 'deep concerns' over the election, said Washington would not meddle in the affairs of Iran.
Supreme leader Ayatollah Ali Khameini earlier pledged to consider a partial recount after the opposition staged massive protests over what it charges was blatant vote-rigging.
The election has triggered days of opposition protests across in Tehran and other cities, exposing deep divisions in the Shia nation of 71m people.
At least seven people have been killed and many more wounded. Witnesses said some clashes also erupted late last night between groups of young men and members of Iran's volunteer Basij militia.
Ahmadinejad remained defiant, saying his landslide victory in last Friday's vote was proof of the people's faith in his government of 'honesty and service to the people.'
In yesterday's demonstrations, supporters of Mr Ahmadinejad and Mr Mousavi staged rival rallies, each calling out hundreds of thousands of people on to the streets of Tehran.
Iranian newspapers published pictures of the demonstrations this morning - foreign media were banned from covering the events.
The restrictions ban foreign journalists from covering demonstrations and effectively confine all non-Iranian media to their offices and hotels.