Turkish news agency Dogan said that at least 20 people have been killed. Photos posted on social media show a number of bodies at the scene.

The blasts took place near the city's central train station.

The target appears to have been a march calling for an end to the violence with the Kurdish separatist group, the PKK.

Prime Minister Ahmet Davutoglu is being briefed by the interior and health ministers, state news agency Anadolu says.

Reports say the government is investigating whether the explosions were a suicide attack.

The pro-Kurdish HDP party was among those calling for Saturday's rally for "peace and democracy", which was due to start at 12:00 local time.

The party tweeted that there were "numerous dead and injured", and that police "attacked" people carrying the injured away.

Local resident Emre told the BBC that he heard two separate explosions and saw a number of dead bodies. Angry people tried to attack police cars, he said.

An HDP rally in the city of Diyarbakir was bombed in June, ahead of general elections.

Turkey is holding another election next month, and the BBC's Mark Lowen in Istanbul says it was feared that another similar attack was imminent.

Courtesy BBC