The UN-backed Electoral Complaints Commission is understood to have ruled that fraud in August's election means Mr Karzai did not gain the 50% of votes he needs to avoid a run-off.
British troops and diplomats are preparing for a possible second round of voting in Afghanistan after investigators rejected many ballots cast for president Hamid Karzai.
The UN-backed Electoral Complaints Commission is understood to have ruled that fraud in August's election means Mr Karzai did not gain the 50% of votes he needs to avoid a run-off.