The validity of Afghanistan's national election was thrown into doubt Saturday after reports of widespread voting irregularities prompted 15 candidates running in opposition to Interim President Hamid Karzai to declare a boycott of the poll, the results of which they say they will not recognize. BBC News has more; see the latest reports from correspondents on the ground in their Afghan election weblog. Afghan election officials nonetheless continued with the vote, which has now concluded. A UN official said Friday that ballot counting is expected to take two to three weeks. Reuters has more.

UPDATE: The United Nations Assistance Mission in Afghanistan has posted this English-language press release from Afghanistan's Joint Election Management Board on the reported irregularities, issued at 4 PM Kabul time Saturday, just as the polls were scheduled to close:

The JEMB has received reports that a number of candidates are alleging a variety of irregularities and problems with the electoral process and calling for the election to be halted and for the votes already cast to be invalidated.

Given the complexities of this electoral process, there have inevitably been some technical problems, which the Electoral Secretariat has been addressing during the day. Nevertheless, the JEMB is encouraged that the voters of Afghanistan have turned out in large numbers and that the process overall has been safe and orderly. The JEMB is also aware that many people are still eagerly waiting in line for their opportunity to vote in this historic election. Halting the voting at this point is unjustified and would deny these individuals their fundamental right to vote.

Accordingly, the JEMB has directed the Electoral Secretariat to continue operations in order to give all eligible Afghans who wish to vote the opportunity to do so.

The JEMB wishes to reassure voters, candidates, and observers that procedures exist to receive, investigate, and decide on complaints. All complaints and irregularities raised with the JEMB will be thoroughly investigated and taken into account when the JEMB deliberates on the extent to which the election accurately reflects the will of the Afghan people.

The JEMB will request, and has received assurances from the United Nations and domestic observer organizations that they will provide, full cooperation in the investigations that will be required. Additional resources will be provided to the JEMB to ensure that these investigations are carried out as expeditiously and thoroughly as possible. Candidates may, as is required by the principle of due process of law, participate fully in the process of hearing and investigating complaints.