KANDAHAR (AFP) - The Taliban on Sunday threatened for the first time to attack Afghan polling stations, escalating their bid to derail key elections this week after striking NATO in the heart of Kabul. The threat was made in leaflets, pinned up and dropped in villages in the south, and authenticated by a Taliban spokesman who said the militia would accelerate its bloody campaign of violence on the eve of polls. Afghanistans electorate of 17 million are to vote Thursday to elect a president for only the second time and 420 provincial councillors in a massive operation clouded by insecurity and logistic headaches. This is to inform respected residents that you must not participate in the elections so as not to become a victim of our operations, because we will use new tactics, said one leaflet distributed in Kandahar city and seen by AFP. The letter was written by Mullah Ghulam Haidar, the guerrillas purported operations commander in Kandahar city. It said voters - as allies of the Afghan government and foreign forces - would be considered enemies of Islam. All people are being informed that you must not rent out property to voting centres and if anyone did - even after elections - they may face problems, said the letter. Taliban spokesman Qari Yousuf Ahmadi confirmed the leaflets were authentic and that commanders were ordering the masses to boycott the vote. We are using new tactics targeting election centres... We will accelerate our activities on election day and the day before, the spokesman told AFP. Meanwhile, Afghan forces backed by NATO-led troops have wrested a district in the troubled south of the country from Taliban control days ahead of landmark elections, authorities said Sunday. The Afghan national flag was hoisted over the centre of Naw Zad district in Helmand province, which had long been controlled by Taliban-linked militia, a defence ministry spokesman said. They were driven out in a major operation launched last month, he said.