Two prominent defeated Iranian presidential candidates said they would maintain their campaign against President Mahmoud Ahmadinejad's re-election, which has sparked Iran's worst unrest since the 1979 Islamic Revolution.
Mr Ahmadinejad will be sworn in by parliament tomorrow and the authorities will want to avoid any repeat of the street unrest after the disputed June 12th poll in which at least 20 people were killed and hundreds were detained.
Leading moderates have accused the government of electoral fraud and have branded the next Ahmadinejad administration as "illegal".
The wife of Iran's opposition leader Mirhossein Mousavi said today he would continue to contest the election result. "Despite all the hardship, we will continue our path to fight against the result" Zahra Rahnavard was quoted as saying by the reformist website Mowjcamp.
Mehdi Karoubi, the most liberal of the presidential candidates, was quoted by the Spanish El Pais daily as saying he too would continue to oppose the government.
"Neither Mousavi nor I have withdrawn. We will continue to protest and we will never collaborate with this government. We will not harm it, but we will criticise what it does," Mr Karoubi said in an interview. "Quite honestly, if the authorities had acted in a different way, we would never have had these problems, because the majority of those protesting only did so for that reason."
US president Barack Obama and the leaders of France, Britain, Italy and Germany have all decided not to congratulate Mr Ahmadinejad on his re-election.
But when asked whether Mr Obama recognised Ahmadinejad as Iran's president, White House spokesman Robert Gibbs said: "He's the elected leader."
The Iranian government says the presidential election was fair and transparent and has accused Western nations, especially Britain and the United States, of being complicit in the bloody post-election unrest, a charge they deny.
Two former presidents, Akbar Hashemi Rafsanjani and Mohammad Khatami, who backed Mr Mousavi's failed presidential bid, boycotted yesterday's endorsement of the president by the Supreme Leader although they were present at such events in the past.
After the ceremony a witness said hundreds of Mr Mousavi supporters, some of them honking car horns, gathered near a central Tehran square, where riot police and Basij militia were assembled to prevent any demonstration.
Mr Mousavi has yet to unveil a promised new political front with his reformist and pragmatist allies, perhaps partly because so many leading figures are in jail, including 100 whose trial for inciting unrest began on Saturday and resumes on Thursday.
New York-based Human Rights Watch said none of the people on trial had been charged with any specific violations of Iranian law and should be released immediately and unconditionally.