Turkish warplanes pounded Kurdish rebel bases in northern Iraq today, the day after a suicide car bomb tore through downtown Ankara killing at least 36 people, the third attack on the capital in five months.

There was no immediate claim of responsibility for the latest carnage, which reduced cars and buses to charred hulks on a busy road in the heart of the city, wounding more than 120 people.

But Ankara believes one of the bombers was a woman with ties to the outlawed Kurdistan Workers' Party (PKK), a Turkish official told AFP on Monday.

Hours after the attack, Turkish fighter bombers hit arms depots and PKK shelters in mountainous northern Iraq, the army said, quoted by the state-run Anatolia news agency.

The strikes came as the government announced three more deaths overnight from Sunday's huge explosion at a bus stop near a busy square in central Ankara.

Health Minister Mehmet Muezzinoglu gave a new overall toll of 37, but said this included at least one attacker and possibly two.

The military said the PKK targets were hit "with precision", with a rebel spokesman confirming the strikes and saying that so far, there was no clear picture of the damage caused.

Sunday's attack bore similarities to another suicide car bombing on a convoy of military buses which killed 29 people in Ankara on February 17, but this time civilians were the target.

The February attack was claimed by the Kurdistan Freedom Falcons (TAK), linked to the PKK, as revenge for Turkish military operations in the southeast. The TAK warned of more attacks to come, including on tourist areas.

Over 40,000 people have been killed since the PKK took up arms in 1984 demanding an independent state for Kurds. Since then the group has narrowed its demands to greater rights and autonomy.

- Government 'didn't warn anyone' -

Prime Minister Ahmet Davutoglu said Turkey had "concrete information" on the group behind Sunday's attack, saying results from the inquiry would be made public soon.

"One attacker is believed to be a woman with links to the PKK," a Turkish official told AFP. Local media reported her name as Seher Cagla Demir, saying she was identified by fingerprints.

Officials say the attack deliberately targeted the bus stop close to Kizilay square, a bustling commercial and transport hub near the parliament, prime minister's office and foreign embassies.

The fact that extremists were able to strike again in the heart of the capital, so close to so many sensitive buildings and so soon after February's attack will raise questions about Turkey's ability to deal with the twin threat of Kurdish rebels and the Islamic State (IS) group.

Turkey has been hit by a string of major attacks since the middle of last year, most of them blamed on IS. Three have targeted Ankara, including a double suicide bombing in October that left 103 people dead.

President Recep Tayyip Erdogan's party won parliamentary elections four months ago campaigning as the only sure bulwark against rising insecurity, but the ongoing bloodshed is causing anger.

"People have been talking about another bomb attack coming for more than a week but the government took no precautions and didn't warn anyone," Nihat Gorgulu, the uncle of one of the victims, told AFP.

"We are very afraid because the government doesn't care about the people of this country."

As recently as Friday, the US embassy issued a warning about a possible plot to attack a part of central Ankara close to Sunday's bombing, advising American citizens to avoid the area.

- 'Red flame' -

One man told AFP he escaped death on Sunday by flinging himself out of his car.

"It exploded, there was a red flame that came out," he said, adding that the force of the blast pushed his car backwards. "I threw myself out and then I can't remember anything else."

Ankara rejected the TAK claim for February's attack, insisting it was the work of the Syrian Kurdish People's Protection Units (YPG), which it regards as a branch of the PKK. Both organisations have denied it.

Since December, Turkish security forces have been waging a major campaign against the PKK following the collapse of a ceasefire in the middle of last year.

"The 'uprising' launched by the PKK has not worked. Even the Kurdish population has distanced itself from its operations in the southeastern towns," Can Acun, an analyst with Turkish thinktank SETA, told AFP.

"In frustration the PKK seems to have chosen to go for more serious acts."

Ankara has vowed to wipe out the PKK, classed as a terrorist organisation by Turkey and its Western allies, and Erdogan said late Sunday that the government would "never abandon its right to legitimate defence against the terrorist menace".