Making a major breakthrough, Pakistan police has arrested one person in connection with Tuesday's car blast outside an American fastfood outlet in Karachi.

• Six killed in Karachi twin blasts

"We have arrested the man who is responsible for this. We are trying to find out whom he is representing and his motive," President Pervez Musharraf [Images] told reporters in Rawalpindi.

He said there have been no fresh arrests of Al Qaeda [Images] in the recent days. 

A powerful car bomb exploded outside an American fastfood outlet KFC located in a government building Tuesday, killing six people and injuring 14, besides damaging the restaurant and two luxury hotels nearby.

• Quake hits North India

A lesser-known group called Baluchistan National Army claimed responsibilty for the blast, which took place ahead of the international donors' conference in Rawalpindi on November 19 at which UN Secretary General Kofi Annan is expected to participate to raise 5.2 billion dollars needed for reconstruction of quake-hit areas of North West Frontier Province and Pakistan-occupied Kashmir.

The blast nearly destroyed the KFC outlet located in a government building and caused damage to two luxury hotels -- Pearl Continental and Sheraton -- situated in the vicinity besides a number of banks and commercial offices.

Karachi, the biggest commercial city of Pakistan, has been the scene of several bomb attacks in the past.

In September, several people were wounded when a KFC and a MacDonald restaurant were bombed.

In May, six people were killed when protesters set fire to a KFC outlet in the city, during clashes between religious groups.