Daoud Ali Najafi gave no details, but a second senior official on the commission also confirmed the second round has been called off.

President Hamid Karzai had already effectively secured a second term when his only challenger, former Foreign Minister Abdullah Abdullah, dropped out of the race Sunday because he said the vote would not be free or fair. The first round was marred by massive fraud. THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

KABUL (AP)—U.N. Secretary-General Ban Ki-moon says world body's work will continue in Afghanistan despite the slayings of U.N. staff in Kabul last week.

Ban told reporters Monday in the capital that "we cannot be deterred, we must not be deterred. ... The work of the United Nations will continue."

Last Wednesday, insurgents stormed a guest house in Kabul where U.N. election workers were staying, killing five U.N. staffers and three Afghans.

On Monday, the world body announced it would suspend long-term development work in areas of Pakistan along the Afghan border because of violence.
Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.