By Sayed Salahuddin and Maria Golovnina
KABUL (Reuters) - President Hamid Karzai defended Afghanistan's disputed presidential election on Thursday after preliminary results showed he won, and a suicide bomb attack on Italian troops tested the resolve of a major NATO ally.
Sixteen people, including six Italian soldiers, died in the attack on an Italian military convoy within walking distance of the presidential palace in the capital Kabul, minutes after Karzai held a news conference there.
It was his first meeting with reporters since the August 20 election and he praised Afghans for braving violence to vote.
The strike, the deadliest on Italian forces in Afghanistan, caused shock back home as European leaders scramble to bolster flagging support for the eight-year-old war.
The United States and its NATO allies have more than 100,000 troops in Afghanistan to bolster the government in its fight against Taliban insurgents and prevent the country being used as a base for militant attacks abroad.
The disputed election has further eroded public backing among NATO allies for the war effort, at a time when U.S. President Barack Obama is considering whether to send more troops and European allies are debating whether to quit.
Italian Prime Minister Silvio Berlusconi said Italy planned a "strong reduction" in its 3,100 troops in the wake of the election, but would not unilaterally withdraw.
"We are all anxious and hopeful to bring our boys home as soon as possible," Berlusconi told reporters on arrival in Brussels, where he was due to attend an EU summit.
Italy's contingent had been increased by 500 ahead of the Afghan elections and these troops could be brought home "in the coming days or weeks," in consultation with Italy's allies.
Complete preliminary results released on Wednesday showed Karzai winning the election in a single round with 54.6 percent of the vote, enough to avoid a run-off against his main challenger, former foreign minister Abdullah Abdullah.
The definitive result could take weeks or months. A U.N.-backed watchdog has ordered a recount of 10 percent of polling stations after finding "clear and convincing evidence of fraud."
Karzai played down suggestions fraud could have been big enough to overturn the outcome and force a run-off.
"Like other elections of the world ... there were problems and sensitivities in the Afghanistan elections, but it has not been to the extent which the media speak of," he said.
"I believe firmly, firmly in the integrity of the election and the integrity of the Afghan people, and the integrity of the government in that process."
"TRUE AND FAIR"
Later, in an interview with CNN, Karzai blamed electoral fraud on security problems, adding: "I can assure you, the vote was true and fair."
Western officials initially hailed the August vote, mainly because attacks by militant insurgents failed to prevent it from taking place. Their response has since become more equivocal.
An EU observer mission has said more than a third of Karzai's votes might be suspect because of fraud. Karzai's campaign has called those claims "irresponsible."
Abdullah says fraud played a decisive role and needs to be removed in the complaints process for the result to be valid.
"A golden opportunity for Afghanistan has turned into a disastrous situation," Abdullah told reporters, adding he was not interested in Karzai's offers of a government post.
"My position is not to get a post from the government but to bring change. That will remain my agenda. I am not interested in a coalition government."
ATTACK IN KABUL
Taliban insurgents claimed responsibility for the suicide strike in Kabul in a text message sent from a phone number used by a Taliban spokesman.
At the scene, Afghan troops ferried wounded civilians to ambulances near several wrecked Italian military vehicles.
The body of at least one dead Italian soldier lay in the street in front of an armored truck that bore an Italian flag. Other body parts were scattered near the scene. The chassis of an exploded car landed dozens of meters away.
Most of Italy's conservative government and the main center-left opposition broadly support the Afghan mission. Interior Minister Roberto Maroni said pulling out Italian troops "would mean surrendering to the logic of terrorism."
The far left restated demands for an immediate withdrawal.
Record military and civilian deaths and uncertainty over the election result have raised questions among Washington's allies, particularly Britain and Germany, about how long their troops should remain or if they should be there at all.
Obama may also find it hard to persuade Americans to send more troops to defend a government whose legitimacy could be called into question due to large scale fraud.
U.S. Defense Secretary Robert Gates told reporters in Washington that any decision to deploy additional U.S. troops should not be rushed, adding that "the nature of the election in Afghanistan has complicated the picture for us."
U.S. Vice President Joe Biden, visiting Iraq, also said it was too early to talk about additional troops.
The British army's new commander, General David Richards, said Western forces had to find the right tactics to defeat the Taliban as they had in Iraq, which was about to implode 18 months ago.
"The ingredients for success in Afghanistan are similar, but we have not yet confirmed the correct formula for that country," he said in a speech at the Chatham House think-tank.
(Additional reporting by Reuters bureaux; Writing by Peter Graff and Maria Golovnina; Editing by Jon Boyle)