ISTANBUL, Oct 12 - Turkey's government said on Monday Islamic State was the prime suspect in suicide bombings that killed at least 97 people in Ankara, but opponents vented anger at President Tayyip Erdogan at funerals, universities and courthouses.

Prime Minister Ahmet Davutoglu said Saturday's bombing, the worst of its kind on Turkish soil, was intended to influence the outcome of November polls Erdogan hopes will restore the AK party he founded to an overall parliamentary majority. There is no question of postponing the vote, officials have said.

"It was definitely a suicide bombing," Davutoglu said in an interview broadcast live on Turkey's NTV. "DNA tests are being conducted. It was determined how the suicide bombers got there. We're close to a name, which points to one group."

Opponents of Erdogan, who has led the country over 13 years, blame him for the attack on a rally organised by pro-Kurdish activists and civic groups, accusing the state at best of intelligence failings and at worst of complicity by stirring up up nationalist, anti-Kurdish sentiment.

The government, facing a growing Kurdish conflict at home and the spillover of war in Syria, vehemently denies such accusations.

The sheer range of possible perpetrators - from Islamic State and Marxist radicals to militant nationalists and Kurdish armed factions - highlights fissures running through Turkish society. At stake is the stability of NATO country seen by the West as a bulwark against Middle Eastern turmoil.

Hundreds chanting anti-government slogans marched on a mosque in an Istanbul suburb for the funeral of several of the victims, attended by Selahattin Demirtas, leader of the pro-Kurdish parliamentary opposition Peoples' Democratic Party (HDP), which says it was the target of the bombings.

Riot police with water cannon and armoured vehicles stood by as the crowd, some chanting "Thief, Murderer Erdogan" and waving HDP flags, moved towards the mosque in the working class Umraniye neighbourhood of Istanbul.

Several labour unions also called protests. Hundreds of people, many wearing doctors' uniforms and carrying Turkish Medical Association banners, gathered by the main train station in Ankara where the explosions happened to lay red carnations but were blocked by riot police, a Reuters witness said.