By Jonathan Spicer, Ali Kucukgocmen and Ece Toksabay
ISTANBUL (Reuters) - 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."
ECHOES OF PAST ATTACKS
Six Turkish citizens, two members each of three families, were killed in the attack.
Social worker Yusuf Meydan and his nine-year-old daughter died during the attack while his wife was inside a shop and survived the blast, according to Demiroren agency.
The Meydan family was supposed to go back to their hometown Adana on Sunday after attending an engagement ceremony of a relative in Istanbul, the cousin of Yusuf Meydan said in an interview with Demiroren.
"They went there for an engagement ceremony of a relative...they were supposed to come back last night. They wanted to visit Taksim and that incident happened. I condemn terrorism. There is nothing else to say," Meydan's cousin said.
Authorities said 24 of the wounded, including two in critical condition, were still in hospital, while another 57 people were discharged after treatment.
The attack sparked concerns that more such incidents could occur ahead of elections set for June 2023, which polls suggest President Tayyip Erdogan could lose after two decades in power.
Istanbul has been attacked in the past by Kurdish, Islamist and leftist militants. A wave of bombings and other attacks began nationwide when a ceasefire between Ankara and the PKK broke down in mid-2015, ahead of elections in November that year.
"It has been a disaster," said Lokman Kalkan, who was sweeping shattered glass and bloodstains from the floor outside his suitcases shop near the blast site. "This is all that happened. People were fighting for their lives."
Turkey has carried out three incursions in northern Syria against the YPG and Erdogan said this year another operation was imminent.
The PKK has led an insurgency against the Turkish state since 1984 and more than 40,000 people have been killed in clashes. It is considered a terrorist organisation by Turkey, the European Union and the United States.
(Additional reporting by Bulent Usta; Editing by Simon Cameron-Moore, Gerry Doyle, Alex Richardson, William Maclean)