Turkey on Saturday prepared for its tightest elections in over a decade, with tensions riding high after a bomb attack killed two and wounded dozens at a rally of the main pro-Kurdish party.

Judicial sources said the explosion at a rally of the pro-Kurdish People's Democratic Party (HDP) in southeastern city of Diyarbakir was caused by a cylinder bomb packed with hundreds of ball bearings.

The ruling Justice and Development Party (AKP) wants to take a large majority in Sunday's legislative elections and change the constitution to give Turkey's charismatic but divisive President Recep Tayyip Erdogan more power.

But polls have indicated that its vote could be well down on the almost 50 percent score the AKP reaped in the last elections in 2011 and may even need to form a coalition.

The government has not yet confirmed that the Diyarbakir blast was the result of a bomb attack and initial reports had suggested it was due to a faulty electricity transformer.

But judicial sources in Diyarbakir told AFP that investigators had confirmed that the explosion was caused by a bomb.

"The experts collected hundreds of ball bearings and pieces of the metal cylinder," said a source, who asked not to be named.

The source confirmed that no suspect had yet been arrested over the blast but fingerprint and video evidence had been found.

In a statement, Diyarbakir prosecutors confirmed that two people had been killed and over 100 wounded.

The funeral was held Saturday morning for one of those killed, Ramazan Yildiz, who was only 17, an AFP photographer reported.


'Hold AKP to account'

The blast was the latest strike in the campaign against the HDP, which represents Turkey's Kurdish minority but is increasingly reaching out to secular Turks.

It has already seen one of its drivers shot dead, regional offices attacked and one of its other rallies stormed by nationalists.

Prime Minister Ahmet Davutoglu said the attack was an "open provocation" that "targeted our democracy and Turkey's stability."

President Recep Tayyip Erdogan said in a television interview late Friday that the strike were a "bid to overshadow the elections."

The explosion resulted in the cancellation of the HDP's Diyarbakir rally, one of the centrepieces of its campaign, where party leader Selahattin Demirtas was due to give a speech.

Demirtas later urged supporters not to take to the streets and show moderation, tweeting that "peace will win".

Several thousand people Saturday held a sit-in protest at the scene in Diyarbakir, waving HDP flags and chanting the "AKP will be held accountable."


'Last day of campaigning'

The HDP has been leading an energetic campaign aimed at surmounting the tough 10 percent vote barrier needed to send MPs to the Turkish parliament.

Should it succeed, the party could wreck the plan of the AKP to take a large majority and change the constitution to give Erdogan more powers.

In a bitter and personal campaign, Erdogan had launched a series of attacks against Demirtas, rubbishing him as a "pretty boy" who is acting as a front for Kurdish militants.

Turkey's political leaders were making a final push for votes Saturday ahead of the early evening legal deadline for campaigning to end.

Davutoglu, his voice reduced to a croak by the strain of a marathon campaign, was due to wind up his tour in his home region of Konya in central Turkey.

The participation in the campaign of Erdogan, who served as premier from 2003-2014 is hugely controversial, as since becoming president in August last year he should have severed his links with party politics.

Polls have indicated that the election is on a knife-edge with the HDP's rating hovering just at or below the all-important 10 percent threshold.

The AKP has been under greater pressure than in previous polls, with the economy losing some of its former sparkle and controversy growing over what critics say are Erdogan's authoritarian tendencies.

The main opposition Republican People's Party (CHP) is expected to come second followed by the Nationalist Movement Party (MHP) and then the HDP in fourth.