But the Kurdistan Workers' Party denied any role in the bombing.
"We announce that we ... have no connection with this attack and that we do not approve of such methods," said a statement from the PKK, which has been fighting for self-rule in Turkey's southeast since 1984.
The statement was published on the website of Firat, a pro-Kurdish news agency.
Turkish police on Wednesday detained a suspected suicide bomber in possession of 11.3 kilograms of plastic explosives in the southern city of Adana, the local governor said.
Ilhan Atis, the governor of Adana, told the Anatolia news agency that police, acting on a tip-off, detained a woman who tried to flee when officers stopped the vehicle she was travelling in.
Her bag contained the plastic explosives, two hand grenades and 12 detonators, Atis said.
"It is understood that she is a suicide bomber."
The governor did not say whether the woman belonged to any group and said a detailed statement would come after she is questioned.
In a related development, Turkey's government convened an emergency meeting on countering terrorism on Wednesday.
"Whatever system the Turkish majority want should be done through elections"
Baz, Vancouver, Canada
Send us your views
Abdullah Gul, the Turkish foreign minister, who is also deputy prime minister, chaired the emergency meeting, attended by intelligence, security and military officials as well as ministers to assess measures for countering terrorism.
No details were immediately available.
The rush-hour explosion at the entrance of a Ankara shopping mall was believed to be the worst in at least a decade to strike the capital and came at a time of heightened political tension in the European Union-aspirant country.
Turkish media said eight people had been detained in connection with the blast. Police declined to comment.
Leading newspapers Hurriyet and Radikal said that the blast took place shortly before senior military commanders, including General Yasar Buyukanit, the armed forces chief of general staff, were due to pass the area to go to a defence-industry reception.