Taliban attacks rocked Afghanistan Tuesday two days before elections as suicide bombers killed more than 12 people, including UN staff and NATO troops, and a rocket slammed into the presidential compound. The violence, striking at the heart of the capital Kabul, followed renewed Taliban threats to sabotage Thursday's ballot when 17 million Afghans will elect a president and heightened fears voters could stay away. A suicide car bomb ripped through a busy road in Kabul used frequently by NATO and US troops, near a US military base and a bustling market, killing seven Afghan civilians and wounding around another 50, officials said. 'Reports indicate both Afghan civilians and ISAF (International Security Assistance Force) service members were killed and wounded in the blast as the vehicle exploded near an ISAF convoy,' said the NATO-led force in a statement. The United Nations in Kabul announced that two of its local Afghan staff were among the dead and that a third was wounded in the second deadly suicide attack targeting NATO in the capital in two days. Most of the victims were civilians. Children were among the wounded and casualties were blackened by burn injuries and bloodied from shrapnel, witnesses said. 'It was a suicide attack... targeting a supply convoy of foreign forces,' said Kabul criminal investigation police chief Sayed Abdul Ghafar Sayedzada. Militants earlier fired volleys of rockets into the capital and the eastern city of Jalalabad, wounding at least 10 people, mostly women and children. A spokesman for President Hamid Karzai, who is the frontrunner widely expected to win Thursday's elections, confirmed that one rocket hit the outer perimeter of the presidential compound. Thousands of US and NATO troops pushed into militant strongholds months before polling day but at least eight districts remain outside state control and up to 12 percent of polling centres may not open, authorities said. In southern Afghanistan, the Taliban's main powerbase, a suicide bomber walked up to an Afghan military checkpoint and blew himself up killing three soldiers and two civilians in Uruzgan province on Tuesday, police said. Although Karzai has been tipped to hold on to power, an energetic campaign by former foreign minister Abdullah Abdullah has boosted the chance of a run-off amid fears that charges of irregularities may lead to protests. The NATO-led force announced it would suspend all offensive operations and focus on protecting the civilian population on election day. US President Barack Obama called for patience overnight, saying defeating the insurgency 'will not be quick. This will not be easy'. American defence officials have said the commander of US and NATO forces in Afghanistan, General Stanley McChrystal, is weighing cutting back desk jobs and other support staff to free up more soldiers for combat. The Taliban were overthrown by the 2001 US-led invasion of Afghanistan but have orchestrated a deadly insurgency against the Western-backed administration and foreign troops, with violence now at record highs. About 300,000 Afghan and foreign troops -- every man available, officials say -- will be deployed to guard between 6,200 and nearly 7,000 polling centres, with the final figure depending on security risks, authorities say. Human Rights Watch (HRW) raised concern Tuesday that the polls could be compromised by low turnout, violence, fraud and intimidation. Between April 25 and August 1, there were at least 13 politically motivated killings and at least 10 abductions of electoral officials, candidates and campaign workers, the New York-based watchdog said. A provincial council candidate in the northern province of Jowzjan was killed in a Taliban ambush late Monday, police said. 'Violence, plans to use irregular security forces at polling stations, unequal access of candidates to state media, and conditions affecting women are of particular concern,' said Brad Adams, Asia director at HRW. Afghanistan's foreign allies are footing the bill for the 223-million-dollar election and have mobilised massive resources to make the ballot a success. Despite fears low turnout could undermine the election's credibility, many are eager to take part. 'If people die then I might die, but I'll still vote knowing the risks,' said Amina, a 35-year-old widow in the southern city of Kandahar. Progress has been made since the collapse of the five-year Taliban regime, but many people are frustrated. Despite billions of dollars of Western aid, most lack electricity, roads are bad, jobs are scarce and corruption rife. 