Any run-off presidential election in Afghanistan could be delayed until next year.
A senior election official says any such event would have to take place before the third week of October or be put off until winter weather lifts.
Chief electoral officer Daoud Ali Najafi has urged the Electoral Complaints Commission to speed up a fraud investigation in order to avoid having to delay a potential second-round poll.
The commission has ordered a recount of 10% of polling stations votes to investigate fraud.
The election was held on 20 August. Incumbent President Hamid Karzai currently has more than 50% of the vote, meaning there is no need for a run-off, but that could change if a significant number of votes are rejected.