Initial investigations indicate that Islamic State militants are responsible for a suicide bomb which killed 30 people in a town near the Syrian border, Turkish Prime Minister Ahmet Davutoglu said.
"Preliminary findings point to it being a suicide attack carried out by Daesh," Davutoglu told a news conference in Ankara on Monday (local time), using an Arabic name for Islamic State (IS). "But we are not at a point to make a final judgment."
Davutoglu said the bomber had not yet been identified.
The bomb attack ripped through a cultural centre in Suruc, a town opposite the Syrian flashpoint of Kobane, leaving 30 people dead and 104 wounded.
Davutoglu denounced it as a "clearly terrorist attack" which targeted Turkey's peace, democracy and public order.
"This attack targets us all," he said, urging all political parties and people to demonstrate unity.
The pro-Kurdish HDP party blamed the Davutoglu government for a security and intelligence vacuum in relation to the bombing.
Davutoglu dismissed the criticism and said, "Turkey has always taken measures against Daesh and similar kind of organisations."
Turkish authorities have cracked down on IS networks, arresting dozens of suspects in recent weeks, and beefed up its border with Syria with tanks and anti-aircraft missiles as well as additional troops.
The prime minister said it was obvious that the measures had caused discomfort within IS.
"Daesh constitutes a threat not only to Syrian people but also to Turkey," he stressed.