Turkey blamed Kurdish militants on Monday for an explosion that killed six people in Istanbul and police detained 47 people including a Syrian woman suspected of planting the bomb.

No group has claimed responsibility so far for Sunday's blast on the busy pedestrian Istiklal Avenue, and the Kurdistan Workers Party (PKK) and Kurdish-led Syrian Democratic Forces (SDF) denied involvement in it.

The explosion wounded 81 people, sending debris flying into the air and hundreds of shoppers, tourists and families fleeing from the scene.

Interior Minister Suleyman Soylu said the PKK and the Syrian Kurdish YPG militia were responsible for the blast, an incident that recalled for Turks similar attacks in years past.

Ankara says the YPG is a wing of the PKK. The United States has supported the YPG in the conflict in Syria, stoking friction between NATO allies.

As international condemnation of the attack poured in, Soylu, a fierce critic of Washington, likened U.S. condolences for the victims to "the murderer arriving as one of the first at the scene of the crime".

In a statement on its website, the PKK denied involvement and said it would not attack civilians. SDF commander Mazloum Abdi denied involvement on Twitter.

Police named the suspected bomber as Ahlam Albashir, a Syrian national, who was detained in an overnight raid.

According to police, Albashir said during questioning that she was trained by Kurdish militants and entered Turkey through Afrin, another northern Syrian town.

Earlier television news reports showed images of a person, who appeared to be a woman, leaving a package below a raised flower bed in the middle of the avenue just before the attack.

A Turkish official said the possibility of Islamic State being responsible for the attack was "not entirely disregarded."