The US President, Barack Obama, has welcomed the decision to hold a second round in Afghanistan's presidential election.
Mr Obama described the development as an important step forward for democracy.
Afghan President Hamid Karzai has also hailed a second round run-off against his main rival Abdullah Abdullah.
The new election date, 7 November, was announced after a UN-backed Afghan complaints commission confirmed staggering levels of fraud in the 30 August presidential vote, declaring more than one million ballots suspect.
‘This is not the right time to discuss investigations, this is the time to move forward to stability and national unity,' Mr Karzai told a news conference.
‘I call upon our nation to change this into an opportunity to strengthen our resolve and determination, to move our country forward and to participate in the new round of elections,’ he added.
Leading US Senator John Kerry welcomed the announcement of a run-off election as a 'great opportunity'.
'I'm proud to stand here with the president of Afghanistan for what I believe is a very important moment for this country,' Mr Kerry told a joint news conference with Afghan President Hamid Karzai in Kabul.
'With Afghanistan facing extraordinary challenges a moment of great uncertainty has been transformed into a time of great opportunity', he said.
