Afghan presidential candidate Abdullah Abdullah speaks during a gathering with his supporters in Kabul November 1, 2009. Abdullah quit an election run-off on Sunday after accusing the government of not meeting his demands for a fair vote, but said he was not calling for a boycott.(Xinhua/Reuters Photo)

Afghan President's top challenger Abdullah Abdullah announced Sunday (Nov 1) that he would not participate in the run-off presidential election set on Nov 7.

"It is unnecessary to participate in an election full of fraud," Abdullah told his supporters in a gathering in Kabul. "I made this decision for larger interest of the country and for strengthening democracy in the country."

"This is a very tough decision," Abdullah said. "I took in a lot of consultation with our people before I made the decision."

According to the constitution, it is possible for the run-off to be held with only one candidate, but that is believed to undermine the government's legitimacy.

The announcement came after talks of forming coalition government between Karzai and Abdullah broke down on Saturday, local media reported.

Abdullah put forward some conditions one week ago to ensure the credibility of the run-off, including replacing top election official and suspending three ministers. The first-round election was affected by widespread fraud, according to a UN report.

The first-round election was held on Aug 20, with preliminary results by Afghan election authority showing Karzai won 54.6 percent. However, a UN investigation on fraud pushed Karzai's total to below the 50 percent, which is needed to avoid a run-off.

　　Afghan presidential candidate Abdullah Abdullah answers questions from the international media at his house in Kabul Nov 1, 2009.(Xinhua/Reuters Photo)

U.S. President Barack Obama is weighing his strategy on Afghanistan and considering whether to send tens of thousands additional troops to the war-torn country while Taliban has vowed to disrupt the run-off election.

Editor: Miranda