The Islamic State (IS) group is the prime suspect in the Ankara bombings that killed nearly 100 on Saturday, Turkish PM Ahmet Davutoglu has said.
No group has said it carried out the attack, but the government believes that two male suicide bombers caused the explosions, hitting a peace rally.
The official death toll is 97, but one of the main groups at the march put the number of dead at 128.
The funerals of more of the victims are taking place on Monday.
Saturday's twin explosions ripped through a crowd of activists outside the main railway station in the Turkish capital.
They were due to take part in a rally calling for an end to the violence between Turkish government forces and the militant Kurdistan Workers' Party (PKK).
There is anger in Turkey that authorities were unable to prevent such a major attack - and some scepticism from opposition groups about the government's claims.
Mr Davutoglu said authorities were close to identifying one of the suicide bombers, using DNA tests, and that this would help to pinpoint which group was responsible.
He had previously said that IS, the PKK and far-left groups were all capable of such an attack.
Some local media have implicated the brother of a man who carried out an IS bombing in the southern border town of Suruc in July, which killed more than 30 people.
There are also reports that investigators believe there are similarities between the device used in that attack and those used on Saturday.
Turkey announced after the Suruc bombing that it would allow its southern Incerlik airbase to be used by the US-led coalition targeting IS in Syria. Turkey, a Nato member, shares a long land border with its unstable southern neighbour.
The Ankara bombings are the deadliest in Turkey's history.
"These attacks will not turn Turkey into a Syria," Prime Minister Davutoglu said on Monday.
Speaking on Turkish television, Mr Davutoglu said the bombings were an attempt to influence elections due on 1 November, after a vote in June left no party able to form a government.
Many of the victims were activists of the pro-Kurdish HDP party, which says it is now considering cancelling all election rallies. It believes its delegation at the march was specifically targeted.
The HDP gained parliamentary seats for the first time in June's vote, depriving President Recep Tayyip Erdogan's AK Party of its majority.
The AK Party condemned the attack and announced it was suspending all of its rallies until Friday.
In a statement released on Monday, the HDP's leaders said the AK Party was using "escalation of violence" as a strategy to push the leftist, pro-Kurdish party back under Turkey's high electoral threshold for entering parliament.
They link the Ankara bombings to the Suruc attack and the fatal bombing of an HDP electoral rally in June, labelling them a "chain of massacres", and call on the international community to take "a firmer stance" with Turkey's government.
The situation in Turkey was tense even before the Ankara bombings. The ceasefire with the PKK had broken down and there had been clashes between the militants and security forces, killing at least 150 since July.
On Saturday the PKK unilaterally declared a new ceasefire. However, this was rejected by the Turkish government, which carried out cross-border air strikes on PKK positions in southern Turkey and Iraq on Sunday.
The BBC's Mark Lowen in Ankara says critics of the Turkish government believe it is using IS as a scapegoat - and that murky elements of a so-called "deep state" are to blame for the bombings.