AFP/Ankara

Turkish Prime Minister Ahmet Davutoglu on Monday said the Islamic State (IS) extremist group was the prime suspect in  the double suicide bombings in Ankara that killed 97 and sparked anger over the authorities' failure to ensure security.

In his first interview since Turkey was scarred on Saturday by its deadliest ever attack, Davutoglu insisted that snap elections would go ahead as planned on November 1 despite the bloodshed.

The attack on a peace rally of leftist, labour and Kurdish activists ratcheted up tensions to new heights in Turkey as the government wages a relentless campaign against Kurdish militants and grapples with the presence of IS jihadists just inside the border with Syria.

"Looking at how the incident took place, we are probing Daesh as our first priority," Davutoglu told NTV television, using an alternative Arabic acronym for IS.

He said that the attacks were carried out by two suicide bombers.

"We are close to a name (for one bomber). That name points to an organisation," he said.

Davutoglu however remained cautious, saying that authorities were investigating three groups including Islamic State but also the outlawed Kurdistan Workers' Party (PKK) and the far-left Revolutionary People's Liberation Party-Front (DHKP-C) as "potential suspects."

With international concern growing over Turkey's stability, German Chancellor Angela Merkel was to visit Sunday to discuss Turkey and Syria, a spokesman said.

- 'No delay for elections' -

Rallies in the wake of the bombings have been hugely critical of President Recep Tayyip Erdogan, with demonstrators chanting slogans like "Erdogan murderer" and accusing the government of failing to prevent the attacks.

"We lost many friends. But the government must know that we will not step back. We will continue to fight and will fight even harder," labour activist Vassaf Turgut told AFP in Ankara.

But Davutoglu denied there had been any security or intelligence failure. "It is not possible to talk about a failure in general," he said.

He dismissed fears Turkey could be facing civil war like neighbouring Syria.

"This attack will not turn Turkey into Syria."

Erdogan, in a written statement, has condemned the "heinous" attacks as an attempt to break the country's unity.

However the Turkish strongman has remained uncharacteristically silent in public since the attacks. On Monday he has a range of top level meetings programmed including with spy chief Hakan Fidan, army head Hulusi Akar and Davutoglu.

The attacks came with Erdogan under huge political pressure as Turkey heads into the November 1 snap elections.

His ruling Justice and Development Party (AKP) failed to keep its overall majority in June 7 polls and then could not form any coalition.

Erdogan called repeat elections for November 1 but opinion polls are showing that that the result appears likely to be much the same as before.

Some commentators suggested that the Ankara attack could prompt the government to postpone the polls but Davutoglu insisted they would go ahead.

"We will hold the elections under whatever circumstances,"  he told NTV.

- 'Like Suruc bombing' -

The bombings had several parallels with a suicide bombing on July 20 against pro-Kurdish peace activists in the town of Suruc on the Syrian border that was blamed on IS and killed 34.

Turkish press reports said that investigators believed the type of bombs used in Suruc and Ankara were similar. The same forensic experts who worked in the aftermath of Suruc have now been sent to the Turkish capital.

As investigators examine the theory that IS jihadists were behind the blasts, the Hurriyet daily reported that the authorities had taken DNA samples from families of 16 people suspected of being members of the group.

They are also examining the theory that the missing elder brother of the Suruc suicide bomber Abdurrahman Alagoz could have carried out one of the suicide attacks, it added.

Turkish authorities have since Sunday arrested over 40 suspected members of IS across the country, but it is unclear if the raids had any link with the Ankara attacks.

The Suruc bombing caused one of the most serious flare-ups in Turkey in recent times as the PKK accused the government of collaborating with IS and resumed attacks on the security forces after a truce of more than two years.

The military hit back, launching a "war on terror" against the Kurdish militants.

The PKK on Saturday unexpectedly announced it would suspend all attacks -- except in self defence -- ahead of the polls.

But the Turkish army kept up its campaign with more air raids on southeast Turkey and northern Iraq over the weekend, killing 49 suspected militants.