Budapest - A NATO withdrawal from Afghanistan would lead to a strengthening of al-Qaeda and cause instability to spread through the region, NATO Secretary General Anders Fogh Rasmussen said on Thursday in the Hungarian capital.

Rasmussen spoke of the possibility of a gradual handover of power to Afghan security forces beginning as early as next year, the state news agency MTI reported.

The NATO head was speaking at a conference in the Hungarian parliament building on the day Afghanistan's President Hamid Karzai was sworn in for a controversial second term in office.

Hungary's foreign minister Peter Balazs called for closer cooperation between NATO and the European Union during the conference to mark 60 years of the military alliance. (dpa)