Turkish PM Ahmet Davutoglu has pledged to bring to justice the killers of leading pro-Kurdish lawyer Tahir Elci.

Mr Elci was shot dead in the south-eastern city of Diyarbakir during a battle between police and unidentified gunmen. Two policemen also died.

Mr Elci had been making a speech appealing for peace between security forces and Kurdish separatists when he was shot.

The pro-Kurdish HDP Party called his death a "planned assassination".

Later, Turkish police used water cannon and tear gas to disperse hundreds of people in Istanbul who were protesting against the killing.

The incident also sparked protests in Ankara, Izmir and Diyarbakir and a curfew has been imposed in the district where Mr Elci was shot.

Mr Davutoglu promised to hold a "transparent" investigation into the killing.

"One possibility is that after this terror attack, the assailants assassinated Mr Elci," he said.

"A second possibility is that... Elci got caught in the crossfire."

Mr Elci, who was head of the Diyarbakir Bar Association, had previously been detained and received death threats after saying the outlawed Kurdistan Workers' Party (PKK) should not be regarded as a terrorist organisation.

A ceasefire between the army and the PKK collapsed in July and dozens have since been killed in violence.

Moments before he was shot, Mr Elci said: "We do not want guns, clashes and operations here."

Witness Nazim Baran Vurak, a lawyer, said the speech had just finished when gunshots rang out.

"Police immediately reached for their guns and people hid wherever they could," he said.

"Then our friends told us that a man was lying face down on the street and he looked a lot like Tahir Elci."

The BBC's Mark Lowen in Turkey says government supporters are blaming the PKK for the attack while opponents blamed Turkish nationalists.

Turkish President Recep Tayyip Erdogan said he was saddened by the death of Mr Elci.

"This incident shows how Turkey is right in its determination in the fight against terrorism," he said.