The Kurdistan Freedom Falcons (TAK), a faction of Turkey's banned Kurdistan Workers' Party (PKK), claimed responsibility for a deadly car bombing in Ankara, which it said was payback for the government's offensive in the restive south-east.
Thirty-seven people were killed in Sunday's attack in the heart of the capital, not far from key government offices. Most of the victims were civilians.
The attack was in retaliation for the "massacre in Kurdistan," a statement on the group's website said, referring to the intensified conflict between Turkish security forces and the PKK.
The group warned of further attacks on its website: "Those who live in Turkey should know that until the fascist dictatorship has been razed to the ground, human life is not safe."
TAK said that the bombing had been aimed at security forces and blamed police intervention for putting innocent lives at risk. It did not explain what role the police had played in allegedly doing so.
Sunday's bombing was the second to be claimed by TAK in recent months. The group, about which little is known, was also behind a February 17 bombing in Ankara that targeted a military convoy, killing 30 people including the attacker.
A two-year ceasefire between Turkey and the PKK collapsed in July amid mutual recriminations and a collapse of peace talks. The Kurdish militants, who have been fighting the state for three decades, are demanding greater autonomy and right for the minority group.
The state stepped up military operations against the PKK and other groups in December.
Since then, hundreds have died, including civilians. There has been wide-scale destruction in some Kurdish districts and more than 350,000 people were displaced.
TAK is seen as a splinter that broke away from the PKK more than a decade ago, though some security experts claim there are still links.
Turkish President Recep Tayyip Erdogan had repeatedly blamed Kurdish militants for the weekend attack in Ankara and vowed Wednesday to unleash an "iron first" against terrorism.
Erdogan also pledged to broaden Turkey's definition of "terrorist" to include those thought to support terrorist organization, drawing criticism from human rights groups.