Speaking in Istanbul, Recep Tayyip Erdogan announced projects to boost economic and social development in Diyarbakir, the largest city of the impoverished Kurdish-majority southeast, where he was to hold a rally later in the day.

Tensions have mounted ahead of the June 12 polls amid a renewed military onslaught on the separatist Kurdistan Workers' Party (PKK) and deadly PKK attacks on police despite a truce the rebels had declared last year.

"We continue to expend efforts -- with patience and determination -- to increase investment in the (Kurdish) region and resolve its problems," Erdogan told a gathering of his Islamist-rooted Justice and Development Party (AKP).

He announced projects to rennovate Diyarbakir's historic walled city, build a new airport, a dam, a stadium, more hospitals and highways as well as recreation facilities at the banks of the Tigris river in the city outskirts.

Drawing on improved services and a sentiment of Islamic fraternity, the AKP has enjoyed solid popularity in the southeast and has about 70 Kurdish lawmakers in the outgoing parliament.

The government however has failed to meet Kurdish demands for broader political freedoms and draw up a clear strategy to cajole the PKK into laying down arms.

Nationalist Kurdish candidates, backed by the Peace and Democracy Party (BDP) -- Turkey's main Kurdish party which is seen close to the PKK -- are the AKP's main election rival in the southeast.

Erdogan has accused the BDP of collaborating with the PKK, which Ankara lists as a terrorist group, and orchestrating violent protests, in which Kurdish youth routinely pelt police with petrol bombs and vandalise public property.

A series of EU-inspired reforms have widely broadened cultural freedom for Turkey's Kurds in recent years: they can today broadcast in Kurdish, teach their language at private courses and use it in political life.

But the Kurds now want autonomy and the PKK appears bent on pressing the demand with arms.

Jailed PKK leader Abdullah Ocalan, who retains his influence despite behind bars since 1999, has warned that "all hell will break loose" unless sporadic contacts officials had had with him in prison are upgraded to full-fledged negotiations to resolve the Kurdish conflict.