First results are due Tuesday in Afghanistan''s hotly contested election, which has been marred by allegations of fraud and tensions as President Hamid Karzai and his main rival claimed the lead.

Officials should release partial results from Tuesday afternoon, but the Electoral Complaints Commission (ECC) has warned the final result, due next month, could be swayed by investigations into some of the 225 recorded abuses.

The United Nations threw its full weight behind the ECC''s investigations and appealed for patience.

"It is not my job to define how significant and how widespread those irregularities have been. That is up to the process that now follows and where the ECC will play a critical role," UN special envoy Kai Eide said.

The Independent Election Commission (IEC) will release results piecemeal, with spokesman Noor Mohammad Noor saying around 10 percent of preliminary figures will be announced on Tuesday.