10 Tourists reported dead after suicide bomb blast in Turkey

At least 10 people are said to be dead and 15 injured after an explosion in Istanbul.

The death toll may include tourists, local media have reported.

State-run news service TRT television said the explosion, which rocked the tourist-heavy area of Sultanahmet at about 10.20am local time on Tuesday, was likely to have been caused by a suicide bomber.

At least one Turkish newspaper has reported that the dead include German nationals, although this has not been verified. 

The German embassy was not immediately able to confirm or deny the claims, but the country's foreign ministry on Tuesday morning advised travellers to keep away from large groups and demonstrations outside of tourist attractions.

 Turkish news agency Dogan reports that six Germans, one Norwegian and one Peruvian tourist are among those injured.

The Istanbul governor's office told agency reporters the explosion had killed at least 10 people, while a statement said 15 others were hurt.

The blast was said to be so powerful it could be heard from several neighborhoods.

Authorities were on Tuesday morning investigating what kind of explosive was used.

The Istanbul governor’s office said the authorities were investigating the type of explosive used and who might have been responsible for the attack. It said ten people were killed and 15 wounded but gave no further details.

 The explosion was very loud,” a worker at a nearby antiques store told reporters.

Sultanahmet is Istanbul’s main sight-seeing area and includes the popular Topkapi Palace and Blue Mosque.

Erdem Koroglu, who was working at a nearby office at the time of the explosion, told NTV television he saw several people lying on the ground following the blast.

It was difficult to say who was alive or dead,” Koroglu said. “Buildings rattled from the force of the explosion.”

State-run agency Anadolu reported several police and medics were sent to the area.

Police have sealed off the area, which includes a park that is home to an ancient Egyptian obelisk.

Turkey suffered two major bomb attacks last year.

More than 30 people were killed in an Islamic State (IS) suicide attack in the town of Suruc, near Turkey's border with Syria, in July.

And a pair of suicide bombs in October outside Ankara's main train station, detonated as people gathered for a peace rally, killed more than 100.

The prosecutor's office said that attack was carried out by a local IS cell.