The blast struck at a delicate moment for Ankara when it is under pressure to reach out to the rebels and cajole them into extending a truce that expires next week.

The minibus, carrying Kurdish villagers, hit the mine near Gecitli, a remote village in Hakkari province near the Iraqi border, a local security source said on condition of anonymity.

Three people were wounded, among them a 15-month-old baby girl.

Television footage showed the red minibus, reduced to a charred tangle of metal, lying on a road snaking among barren hills as a military helicopter landed and villagers converged at the scene.

Prime Minister Recep Tayyip Erdogan appeared to blame the Kurdistan Workers' Party (PKK), which has led a bloody 26-year campaign for self-rule in the mainly Kurdish southeast and is listed as a terrorist group by Ankara.

"We condemn those terrorists... Such incidents will not deter us," Erdogan said in Istanbul. "Terror undoubtedly makes us pay a price but this... will not be left unanswered."

The rebels however denied responsibility, charging that renegade groups within the security forces sought to bully the population of the region, known as a PKK stronghold.

"This outrageous attack by... groups bound to the Turkish state is a move to punish and supress the (Kurdish) people's will for freedom," said a PKK statement, carried by the Kurdish Firat news agency.

The PKK had announced a truce from August 13 to September 20, a period that covered the Muslim holy month of Ramadan and a September 12 referendum on constitutional changes.

Turkey's main Kurdish party, the Peace and Democracy Party (BDP), has urged Ankara to seek dialogue with the PKK for a peaceful solution of the 26-year conflict.

The BDP, which is close to the rebels, also condemned Thursday's attack as a "provocation" by rogue elements of the security forces to undermine peace efforts.

BDP chairman Selahattin Demirtas said the blast led to a cancellation of a meeting between party leaders and senior ministers that had been scheduled for Thursday afternoon.

Kurdish civilians in the past have been the victims of both security forces acting outside the law and the rebels themselves.

In January 2008, a PKK car bomb intended at a military bus killed six people, among them five teenagers on their way to school, in downtown Diyarbakir, the largest city of the southeast.

Hakkari Governor Muammer Turker said investigators were examining three backpacks and a plastic bag containing two detonators, found near the site of Thursday's explosion.

If confirmed as a work of the rebels, the blast would be the bloodiest PKK attack on civilians since July 2008 when two near-simultaneous bomb explosions claimed 17 lives in a residential area in Istanbul.

In remarks to the Spanish daily El Mundo last week, senior PKK commander Murat Karayilan warned that full-scale fighting could resume if Ankara continued its "attacks and detentions of Kurds".

The rebels, he said, would lay down arms if Turkey granted the Kurds regional autonomy similar to that in Spain.

Ankara last year announced a plan to boost Kurdish freedoms in a bid to pressure the PKK into abandoning arms.

But it has ruled out any steps that would jeopardise Turkey's territorial unity and rejected dialogue with the PKK.

The plan has since faltered amid increasing public anger over a series of deadly PKK attacks against security forces since last year.

The PKK took up arms in 1984, sparking a conflict that has claimed around 45,000 lives.