KABUL (AFP) - Top candidates in the Afghan presidential race addressed rallies attended by thousands of cheering supporters on Monday, the last day of campaigning for key elections overshadowed by Taliban threats. Seventeen million voters go to the polls Thursday to elect a president for the second time in Afghanistans history. They will also elect 420 councillors in 34 provinces, in a huge logistical operation handicapped by insecurity. President Hamid Karzai, who has ruled Afghanistan since the US-led invasion overthrew the Taliban regime in 2001, is the frontrunner but a strong campaign by former foreign minister Abdullah Abdullah could force a run-off. More than 10,000 people poured into a Kabul stadium-a once notorious Taliban execution ground-wearing blue baseball hats, waving blue flags, carrying pictures of Abdullah and chanting his name over and over again. In a vote stunt rare for Afghanistan, a helicopter circled overhead, dropping hundreds of leaflets with Abdullahs photo, election sign and number as marked on the ballot paper to help even the illiterate majority vote. Afghan police later arrested the pilots of two helicopters and campaign staff for allegedly violating Kabul airspace by dropping the leaflets. Hey compatriots, wake up, it is time for a big change, said the leaflets written in the three most common Afghan languages, Dari, Pashtu and Uzbeki. Karzai, whose office said eight candidates have now abdicated in his favour, leaving around 30 contenders in the fray, came under fire for alliances with warlords during a first television debate attended by an Afghan head of state. In a 90-minute head-to-head broadcast Sunday, he was criticised by outspoken anti-corruption campaigners, ex-finance minister Ashraf Ghani, and eccentric but popular Kabul lawmaker Ramazan Bashardost, over the alleged deals. Ghani, who is running on a campaign of clean governance, job creation and economic development, addressed a final rally of 5,000 in the eastern Nangarhar province, pledging to replace the corrupt government with a legitimate one. Progress has been made since the collapse of the 1996-2001 Taliban regime, but many people are frustrated. Despite billions of dollars of Western aid, most Afghans lack electricity, roads are bad, jobs are scarce, corruption rife. Afghanistan is expected to mobilise all available 300,000 Afghan and foreign security forces in a bid to protect voting centres and counter fears that poor turnout, because of insecurity, could jeopardise the legitimacy of the polls. The Taliban have threatened to attack polling stations, escalating their bid to derail the polls and destabilise the Western-backed government in the impoverished, rural country where 70 percent of the population are illiterate. NATO deputy commander in Afghanistan, Lieutenant General Jim Dutton, said the success of NATO and US-led military campaigns in southern troublespots had improved security before the elections by wresting territory from the Taliban. Clearly, we are not going to stop there, he told AFP-with troops pressing ahead to clear more areas while holding others we have already taken and ultimately enable economic and social development. In the north, Afghan officials dispatched donkey trains into mountains of the legendary Panjshir valleys, laden with ballot boxes and voting papers, taking voting material to the most remote communities unreachable by road. Most of the animals were led by children. Asked about the election, one of the boys, who wore plastic shoes and said he was 12 years old, said only: For king.