One of the two suicide bombers thought to be responsible for the Ankara attack in which 37 people were killed was a woman.
Evidence has been obtained that she joined the PKK militant group in 2013, Turkish security officials told Reuters.
She was born in 1992 and from the eastern Turkish city of Kars, they said.
The government has said it expects to officially identify the organisation behind the attack later on Monday.
On Monday, Turkey's military carried out air strikes against Kurdish rebel targets in northern Iraq hours after the attack.
The state-run Anadolu news agency said nine F-16s and two F-4 jets raided 18 positions of the Kurdistan Workers' Party, or PKK in the northern Iraq, including the Qandil mountains where the group's leadership is based.
Police detained dozens of suspected Kurdish militants in a southern Turkish city on Monday.
The attacks following the bombing in the Turkish capital on Sunday in which 37 people were killed and at leas 125 injured.
President Recep Tayyip Erdogan has vowed to bring "terrorism to its knees" in response.
A senior government official said authorities believe Sunday's attack was carried out by two bombers - one of them a woman - and was the work of Kurdish militants.
It is the second attack blamed on Kurdish militants in the past month.
"Our people should not worry, the struggle against terrorism will for certain end in success," President Erdogan said.
Turkey's prime minister Ahmet Davutoglu postponed a visit to Jordan following the deadly bombing.
Interior minister Efkan Ala said Sunday's attack would not deter the country from its fight against terrorism.
British Prime Minister David Cameron said he was "appalled" by the atrocity, tweeting: "My thoughts are with all those affected."
US State Department spokesman John Kirby said: "We reaffirm our strong partnership with our Nato ally Turkey in combating the shared threat of terrorism."
Nato secretary general Jens Stoltenberg said: "There can be no justification of such heinous acts of violence."
