Police held back the mourners, including the pro-Kurdish party's co-leaders Selahattin Demirtas and Figen Yuksekdag, insisting that investigators were still working at the site.
Turkey declared three days of mourning following Saturday's nearly simultaneous explosions that targeted a peace rally in Ankara to call for increased democracy and an end to the renewed fighting between the Turkish security forces and Kurdish rebels. The rally was attended by activists, labour unions and members of the pro-Kurdish party, and came just weeks as Turkey holds a new election on Nov. 1.
A group of about 70 mourners was eventually allowed to enter the cordoned off area outside the capital's main train station Sunday to briefly pay their respects for the victims.
The group of mourners then marched toward a central square in Ankara, chanting slogans against President Recep Tayyip Erdogan, whom many hold responsible for the spiraling violence that has plagued Turkey since the summer.
Addressing hundreds of mourners, Demirtas accused the government of failing to prevent the attack.
"The state which gets information about the bird that flies and every flap of its wing, was not able to prevent a massacre in the heart of Ankara," Demirtas said.
There was no immediate claim of responsibility for the attacks, but Prime Minister Ahmet Davutoglu said Kurdish rebels and Islamic State militants were the most likely culprits.
The government announced Sunday that it had appointed two civil and two police chief inspectors to investigate the attack. Yeni Safak, a newspaper close to the government, said investigators had determined that one of the bombers was a male aged about 25 or 30.
The attacks came at a tense time for Turkey, whose security forces have seen renewed fighting with autonomy-seeking Kurdish rebels since July. Hundreds have died in the last few months as a 2012 peace process with the Kurds was shattered.
The fighting was rekindled following a similar suicide bombing in July that killed 33 peace activists near the border with Syria, which authorities said was the work of the Islamic State group.
Critics have accused Erdogan of inflaming tensions and re-igniting the fighting with the Kurds in the hope that the turmoil would rally voters back to the ruling Justice and Development Party, or AKP. Electoral gains by the pro-Kurdish party caused the ruling party, founded by Erdogan, to lose its parliamentary majority in a June election after a decade of single-party rule.
Erdogan, who strongly denies the accusation, condemned the attacks which he said targeted the country's unity and called for solidarity.
Hours after Saturday's bombings, the Kurdish rebels announced a temporary cease-fire to allow the Nov. 1 elections to proceed in a secure environment. Turkey's government has however rejected the declaration, saying the rebels must lay down arms for good and leave Turkey.
The NATO member is also on edge over developments across in Syria, with which it shares a 900 km-long border.
Turkey agreed to take a more active role in the U.S.-led battle against the Islamic State group. Turkey opened up its bases to U.S. aircraft to launch air raids on the extremist group in Syria and carried out a limited number of strikes on the group itself.
Russia has also entered the fray on behalf of the Syrian government recently, bombing sites in Syria and reportedly violating Turkish airspace a few times in the past week. On Sunday, Turkey's military said two Syrian jets and surface-to-air missile systems based in Syria locked radars on three F-16 jets patrolling the Turkish-Syrian border, in a new incident of harassment of Turkish planes from Syria.
Burhan Ozbilici in Ankara, Turkey, contributed to this story.
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