Islamic State is accused to be responsible for the twin blasts that killed at least no fewer than 95 people in Ankara Turkish capital - sources.
Reuters says it has been told that signs shows that the militant group undoubtedly carried out the attack, which a pro-Kurdish political party says left 128 dead.
The HDP (People's Democratic Party), which was among the groups attending the rally, said that 120 of those who died had been identified and eight more bodies yet to be identified.
The government says 95 people died and 245 others were injured by the twin explosions which occurred simultaneously on Saturday morning.
A senior security source that Reuters spoke to said the attack bore a striking resemblance to a suicide bombing in July in the town of Suruc near the Syrian border, also blamed on Islamic State.
The source said: "This attack was in the style of Suruc and all the signs are that it was a copy of that attack ... the signs point to ISIL (Islamic State)."
Protests have been held across the country to denounce the bombings which came at the beginning of a march calling on the government to stop strikes on Kurdish rebels.
There has been no claim of responsibility for the attack - the worst in Turkey's history - but earlier Prime Minister Ahmet Davutoglu said Kurdish rebels, Islamic State militants or leftist groups were most likely to blame.
He also said there was evidence that suicide bombers carried out the blasts.
Co-leader of the HDP, Selahattin Demirtas, accused the Turkish state of bearing responsibility for the attack.
One of the Turkish newspapers claimed that investigators had determined that one of the bombers was a male aged about 25 or 30.
Turkish news agency Dogan reported that police detained 14 suspected members of Islamic State in the central Turkish city of Konya. But is not known whether this was in response to the bombing.
Scuffles broke out on Sunday morning as police used tear gas on pro-Kurdish mourners who attempted to pay their respects to the victims.
Thousands marched towards the centre of Ankara, chanting slogans against President Recep Tayyip Erdogan, who many accuse of increasing tensions with Kurds to profit at the ballot box in November.