Kandahar - A suicide attack at the funeral of a key anti-Taliban cleric on Wednesday killed at least 20 people including one of Afghanistan's top policemen and wounded 52.

Authorities said the bomber was linked to the al-Qaeda network of Osama bin Laden, who was sheltered by the Islamic Taliban before they were ousted, three and a half years ago.

The attack was the worst in Afghanistan this year and one of the most serious since the fall of the Taliban, who claimed Kandahar as their birthplace and who had stepped up attacks in recent months.