The secretary general concludes that a "lack of access to parts of the country owing to the ongoing conflict...seriously hampered the transparency of the elections" but that institutions such as the Electoral Complaints Commission were able to address many problems.
Based on preliminary results, incumbent Afghan president Hamid Karzai is ahead in the polls, with 54.6 percent of the votes declared valid, against 27.8 percent for his main rival, former foreign minister Abdullah Abdullah.
The result will not be finalised until the outcome of a number of investigations into charges of electoral fraud.
If a significant number of votes are invalidated, Karzai's score could edge below 50 percent, forcing him into a second round run-off with Abdullah in a second turn.
"A credible audit and recount process is now coming to its conclusion" after which "it will be of critical importance for the results to be accepted by all so that the election of Afghanistan’s future president can be certified and a new government can be formed", Ban adds.
"The Secretary-General also stated that it is "imperative" that the international community maintain a long-term commitment to Afghanistan, while adding that there must be a "decisive shift" in that relationship", the UN statement said.
"The government must be enabled and determined to assume all the responsibilities that belong to a sovereign State," Ban was quoted as saying.
"The international community, for its part, must play a role that is clearly one of support."
Corruption and incompetence in the Afghan government are regularly condemned by the international community.
Afghans voted on August 20 in the second presidential election in the nation's history.
Provincial elections were held on the same day, with 38.7 percent turnout, according to the electoral authorities, in a poll marked by violence and widespread allegations of fraud.
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