The suspects, remanded in custody after going before a judge last night, were charged with the "fabrication of explosive devices with the intention to kill" and "an attempt to disrupt constitutional order", the official news agency said.
The Ankara prosecutor in charge of the case meanwhile released two other suspects and issued a warrant for nine others accused of playing a part in the October 10 attack that killed 102, the worst of its kind in Turkey's history.
Police suspect the bombers were two young Turks from the city of Adiyaman in the south of the country, a stronghold for Islamist militants, according to Turkish media reports.
One was identified in the reports as Yunus Emre Alagoz, brother of the man who carried out a similar attack in July in Suruc, a town in southern Turkey on the border with Syria, that killed 34 people.
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Prime Minister Ahmet Davutoglu confirmed today that one of the suicide bombers had been officially identified, but would not provide any details to avoid "plunging people into panic".
"One of the terrorists has been identified. We are exploring ties between the attacks on Suruc, Ankara and Diyarbakir," he said in a television interview.
Five people were killed in Diyarbakir in June after a bomb exploded during a pre-election campaign rally for the pro-Kurdish Peoples' Democratic Party (HDP). One man was arrested for involvement in the attack.
Many of those arrested have since been released.
Police yesterday arrested some 50 foreign nationals in a sweep targeting suspected IS jihadists with alleged links to the bombings.
Turkey is the main point of entry to Syria for IS recruits.
The attack has raised political tensions to new highs as Turkey prepares for a snap election on November 1, in a country that has become more polarised than ever.
Pressure has piled on President Recep Tayyip Erdogan, with opposition figures blaming him for security lapses over the Ankara attack and failing to crack down on IS.