Turkey pointed the finger for a bombing in Istanbul on Tuesday, which targeted security forces and killed 11 people, including six police officers, on the banned Kurdistan Workers' Party (PKK).
"All information and signs point to the separatist terrorist organization," Ibrahim Kalin, a spokesman for President Recep Tayyip Erdogan, said Wednesday in Ankara, referring to the banned group. The attack injured 36 people.
No group has yet claimed responsibility for the attack, which occurred in the early morning hours of Tuesday near a touristic hub.
Meanwhile, on Wednesday, four people, including two police officers, were killed and around 30 injured in another car bombing in a town near the Syrian border in south-east Turkey, state-run news agency Anadolu reported.
Officials have also placed the blame for that attack on the PKK which has been locked in battles with security forces in the area in recent months. There has been no direct claim of responsibility.
The bomb went off in Midyat district of Mardin province. Images showed heavy damage to a building, whose front was blown out, and smoke rising from the location where the explosion took place.
Mardin has seen a series of curfews imposed on towns and districts since last year, during fighting between state security forces and Kurdish fighters.
Security forces recently announced that operations in Nusaybin, one of the areas of Mardin seeing the most intense conflict, ended over the weekend, after nearly three months.
A ceasefire and peace process collapsed in July, leading to renewed fighting in a war ongoing for more than 30 years and killing more than 40,000 people. Turkey's government has ruled out a return to peace talks with the PKK, which it views as a terrorist group.
The new round of violence, which is largely focused on the mostly Kurdish south-east, has claimed many hundreds of lives, though some estimates say thousands have been killed.
Many Kurds in Turkey's south-east complain of systemic discrimination by the state, with demands for greater rights and autonomy.
Turkey is also using its air force in the conflict, launching strikes against alleged PKK targets inside the country and in northern Iraq.