Turkish Kurds gathered on Saturday to mourn and protest at the scene of bomb blasts that killed two people and wounded more than 200 at an election rally, with many voicing anger at President Tayyip Erdogan a day before parliamentary polls.

The two explosions, which Erdogan termed a "provocation" designed to undermine Sunday's election, tore through a rally of the pro-Kurdish Peoples' Democratic Party (HDP) in Diyarbakir, largest city in Turkey's mainly Kurdish southeast.

Ball bearings, nails and other metal parts from the device were gathered as evidence but no suspects have been identified, security sources told Reuters.

Hospital sources said more than 200 had sought treatment. A Kurdish political group said more than 300 were hurt.

Chanting "Murderer Erdogan", hundreds marched behind a banner declaring "peace despite everything" to the scene, where they laid red carnations, a witness said.

Erdogan, the most popular politician in Turkey but accused by opponents of authoritarian tendencies, seeks a large majority for the ruling AK Party to furnish him with broader new powers. However, if the HDP clears a 10 per cent hurdle to enter parliament that could thwart his ambitions.

Hundreds joined a convoy of cars heading to the funeral for a 16-year-old boy Ramazan Yildiz. Onlookers made the victory sign and chanted "martyrs don't die" and "AKP you will pay for this".

"If it weren't for Chairman Selahattin there would have been a lot of bloody and violent events yesterday," said retired 61-year-old Mehmet, referring to Friday's call for calm from HDP leader Selahattin Demirtas.

Demirtas has sought to extend support for the HDP beyond its Kurdish core with appeals to centre-left and secular opponents of Erdogan who has assumed an increasingly religious tone in recent months.

Prime Minister Ahmet Davutoglu said "a dirty hand, a provocative hand" had targeted democracy itself.

Witness Guy Martin, a British photographer, told Reuters the blasts occurred some five minutes apart - the first in a rubbish bin and the second in front of a power generator. He saw one person who had lost a leg and others with shrapnel wounds.

"It was a heart-shaking, ribcage-shaking noise," he said. "The most terrifying thing is that crush of people."

Police fired water cannon and tear gas to disperse crowds after the blasts, witnesses said.

Nationalists clashed with HDP supporters at a Demirtas rally in the northern town of Erzurum. Demirtas has said his party has been the target of more than 70 violent attacks during the campaign, including a double bombing in southern Turkish cities last month which wounded six.

He says the HDP will continue to promote peace talks between Kurdish rebels and the government whatever the election outcome.

Erdogan has accused the HDP of being a front for the Kurdistan Workers Party (PKK), which took up arms in 1984 in an insurgency that has killed 40,000 people.

Jailed PKK leader Abdullah Ocalan and Ankara launched peace talks more than two years ago.

Twelve HDP supporters were detained in Istanbul in an operation targeting a PKK youth wing, an HDP spokesman said. Another nine were held in southeast Turkey's Bitlis province.-Reuters