28 killed as powerful explosion rocks Turkish capital Ankara 

ANKARA:  At least 28 people were killed and 61 wounded Wednesday by a car bomb targeting the Turkish military in the heart of the capital Ankara, the latest in a string of attacks to shake the country.

The blast struck a convoy of military service vehicles but it was still not clear who carried it out, said Deputy Prime Minister Numan Kurtulmus, confirming the latest toll.

President Recep Tayyip Erdogan vowed retaliation against the perpetrators of the attack, which came on the heels of a spate of deadly strikes in Turkey blamed on Islamist terrorists but also on Kurdish rebels.

The car bomb detonated when a convoy of military buses carrying dozens of soldiers stopped at traffic lights in central Ankara, creating scenes of panic and chaos.

"This attack has very clearly targeted our esteemed nation as a whole and was carried out in a vile, dishonourable, treacherous and insidious way," said Kurtulmus.

Plumes of smoke could be seen from all over the city rising from the scene, close to the headquarters of the Turkish military and the parliament.

The powerful blast was heard throughout Ankara, sending alarmed residents rushing to their balconies, an AFP correspondent said.

The army said the attack took place at 1631 GMT and had targeted "service vehicles carrying army personnel".

'Right to self defence' 

Without specifying what the retaliation could entail, Erdogan warned that "Turkey will not shy away from using its right to self-defence at any time, any place or any occasion."

"Our determination to respond in kind to attacks taking place inside and outside our borders is getting stronger," he said.

Prime Minister Ahmet Davutoglu cancelled a planned visit to Brussels on Thursday, his office said. Erdogan also shelved a trip to Azerbaijan.

A mini-summit on Europe's refugee crisis gathering 11 EU countries and Turkey scheduled for Thursday was cancelled due to Davutoglu's absence, diplomats said.

In Ankara, ambulances and fire engines were sent to the scene and wounded victims were seen being taken away on stretchers.

Images showed fire-fighters trying to overcome a fierce blaze engulfing wrecked service buses that were gutted by the blast.

Turkish police threw a security cordon around the area. A second blast later rocked the area, the AFP correspondent said, but officials said this was police detonating a suspicious package.

NATO Secretary General Jens Stoltenberg said the alliance strongly condemned the bombing. "NATO Allies stand shoulder to shoulder in the fight against terrorism," he said.

French President Francois Hollande denounced the attack as "odious".

"We are with Turkey and its people in these difficult times," added EU foreign policy chief Federica Mogherini.

 'Perpetrators will be revealed' 

Kurtulmus acknowledged that "we don't have any information yet about who carried out this attack" but vowed the perpetrators "will be revealed as soon as possible."