Lawmaker Hasham Atanwal also died in the attack, said police, as men stormed the house in the capital.

The incident comes less than a week after Mr Karzai's brother, Ahmed Wali Karzai, was assassinated.

Earlier Nato forces began handing the province of Bamiyan to Afghan security forces, the first move of its kind.

Some time after the attack on Mr Khan, the chief of police said security forces and the attackers were still exchanging fire around his house in the western Karti Char district of the city.

Interior ministry spokesman Siddiq Siddiqi said at least two gunmen had been involved in the attack, which began at about 8pm local time (1530 GMT).