KABUL (Reuters) -- A suicide car bomber has killed at least seven people in an attack on a Western military convoy in the Afghan capital and a Taliban rocket hit the presidential palace grounds two days before tense elections.
Security officials said at least 52 were wounded by the bomber, who rammed his explosive-laden vehicle into the convoy on the notorious Jalalabad road, scene of frequent Taliban attacks and home to many Western aid and military compounds.
A spokesman for the International Security Assistance Force (ISAF) in Afghanistan said foreign troops were among the dead and wounded, without elaborating.
Aleem Siddique, a spokeman for the United Nations mission in Kabul, said two Afghan UN staff members were among the dead. He said a UN vehicle had been caught up in the strike but had not been the bomber's target.
With incumbent Hamid Karzai fighting to win a fresh mandate without a second round run-off, the August 20 election is also a test of U.S. President Barack Obama's strategy of escalating the 8-year-old conflict in an effort to reverse recent Taliban gains.
In a speech on August 17
aimed at bolstering public support, Obama called the Afghan conflict "a war worth fighting."
Taliban militants have vowed to step up that fight and disrupt the poll with violence that could damage the election's legitimacy by limiting voter turnout.
Thick black smoke poured from the scene of the suicide bombing and police held back onlookers as the wounded were ferried away in ambulances and pickup trucks.
"I saw wounded people and dead people everywhere," said a shopkeeper named Sawad. "I helped some people to ambulances, their clothes were covered in blood stains."
Several small rockets were fired at the capital overnight. A police source said one caused some damage inside the sprawling, fortified presidential palace compound and a second hit the capital's police headquarters. Neither caused any casualties.
The Taliban claimed responsibility for the rocket attacks on Kabul, the third this month.
In Uruzgan Province in the south, a suicide bomber on foot killed three Afghan soldiers and two civilians at a police checkpoint. A provincial council candidate was shot dead in northern Jowzjan Province.
With civilian and military casualties reaching record levels in the past few months, two more U.S. service members were also killed by a roadside bomb in the east, the U.S. military said. Bullish Assessment
Election campaigning officially ended at midnight after a final day of hectic rallies in support of Karzai and his main rival, former Foreign Minister Abdullah Abdullah.
In a bullish assessment on August 18, Kai Eide, the United Nations special representative for Afghanistan, said he expected the vote would be a success.
"The campaign has exceeded my expectations and I believe they represent a milestone in political maturity in Afghanistan," Eide told a news conference. "I'm not trying to hide that there have been irregularities, but my overall assesment is that this has been a success for the Afghan people."
Polls show Karzai likely to win the vote, but not with the outright majority required to avoid a second round in six weeks. The president is relying on the last-minute support of former guerrilla chieftains in a bid to tip the balance.
Abdullah, an urbane eye doctor, has run an energetic campaign, seeking to garner support from beyond his base in the mainly ethnic Tajik north.
Recent polls give Karzai about 45 percent of the vote to 25 percent for Abdullah. Karzai has secured last-minute endorsements from regional chieftains since the polls were conducted.
Karzai's late reliance on ex-militia leaders such as Uzbek General Abdul Rashid Dostum has raised alarm among his international backers worried that warlords could return to power in the country they dominated for decades.
Dostum, who won 10 percent of the vote in 2004, returned from exile in Turkey late on August 16 to back Karzai.
The United States and the United Nations both expressed concern that Dostum could return to government. Washington said he may have been responsible for human rights violations.
Taliban disruption could hurt Karzai's chance of a first-round win by lowering turnout in southern areas most affected by the insurgency, his ethnic Pashtun heartland.
Karzai said attacks such as the latest suicide bombing would not deter Afghans, who would vote "despite the efforts of the enemies and will show their opposition to their barbaric acts."
More than 30,000 extra U.S. troops have arrived in Afghanistan this year, raising the total number of Western troops above 100,000 for the first time, including 63,000 Americans.
The Western troops will maintain outer perimeter security during the election, with Afghan soldiers and police guarding towns and polling stations. The NATO-led Western force said it would refrain from conducting offensive operations on election day, in line with an earlier pledge from Afghan troops.
On August 15 the Taliban killed seven people and wounded scores in a suicide car bomb attack on ISAF's Kabul headquarters.