The Turkish government says it detained a female member of a Kurdish military group in connection with an explosion that killed six people and wounded 81 others in Istanbul.

The blast occurred Sunday on Istiklal Avenue, a popular tourist spot, in the country's largest city.

Turkish Interior Minister Suleyman Soylu said Monday that investigations found the Kurdistan Workers' Party, or PKK, had carried out the attack.

Government officials are investigating the case as a terrorist attack based on camera footage and eyewitness accounts.

They say the explosion occurred a few minutes after a woman who was sitting on a bench nearby for about 40 minutes left the spot.

The PKK has been waging a separatist armed struggle for the Kurdish minority since the 1980s. The Turkish government says 40,000 people, including civilians, have been killed in the conflict.

The militant group is designated as a terrorist organization not only by Turkey but also by the United States and EU nations.

Turkey has repeatedly called on Sweden and Finland to take measures against the group, which Ankara says is engaged in activities there.

The two Nordic countries have applied to join the NATO military alliance. Turkey is a NATO member.