Istanbul suicide blast injures 32, including 15 police
A suicide bomb blast in the centre of Istanbul has injured 32 people, including 15 policemen.
Police say the bomber tried to board a police bus in Taksim Square. Seventeen civilians were also hurt.
No group has said it carried out the attack, but a two-month-old ceasefire by Kurdish rebels was due to expire later on Sunday, says the BBC's Jonathan Head in Istanbul.
Police identified other bombs nearby and have been working to disable them.
A large explosion was heard throughout central Istanbul just after 0900 GMT.
The explosion took place right next to the independence monument on Taksim Square, which is always crowded with people, our correspondent says.
Those who threaten Turkey's peace, security and development will not be tolerated"
There are usually squads of riot police posted at this part of the square, as it is often the site of demonstrations.
A police spokesman has said he believes they were the target of the explosion, which he said may have been caused by a suicide bomber. Television pictures from Taksim Square showed body parts lying on the ground.
Eyewitness Aris Virkas told the BBC that he was walking through Taksim Square when he heard the blast.
"I turned around and saw policemen with blood on their face and someone lying on the ground," he said. "People, including police, were running around in panic.
"There was a big bus with maybe 20 police officers: they ran out of the bus, trying to find out what's going on.
"After a couple of minutes, they started asking people to step back."
Our correspondent says suspicion is likely to fall on Kurdish separatist factions, or groups linked to al-Qaeda.
Mr Erdogan was in Mardin in south-eastern Turkey where most of the Kurdish minority live, Kazinform cites BBC. See www.bbc.co.uk for full version.