Turkish President Recep Tayyip Erdogan said a Syria-linked suicide bomber was behind the blast in Istanbul that killed at least 10 people and wounded 15 others on January 12. 

The Turkish authorities have immediately imposed a media ban on the coverage of the blast. The cause of the explosion was not immediately known and no group has claimed responsibility.

CNN Turk reported that nine of the 10 victims were Germans. One Norwegian, one Peruvian and six German and tourists were also injured in the explosion, according to the private news channel. Germany's Foreign Office issued a travel advisory following the blast. Turkey is a popular destination for German tourists.

The explosion occurred at around 10:15am local time on January 12 in the Sultanahmet square, close to the Blue Mosque, a major tourist attraction. 

Just over a year ago, a female suicide bomber blew herself up near the Sultanahmet square. One police officer was killed and another officer was wounded in the attack. The radical leftist group DHKP-C initially claimed responsibility for the attack, but later denied it. Officials later revealed that a Russian citizen with Islamist links carried out the attack.

The Istanbul blast comes at a time Turkey is dealing with multiple threats to its security. Violence has intensified between  security forces and the Kurdistan Workers’ Party (PKK) militants, after a two-year ceasefire broke down in July. Security forces are carrying out large scale operations against Kurdish militants in several Kurdish towns in the country’s southeast.

The PKK does not target civilian targets in the western part of the country. But a radical splinter group, the TAK- Freedom Falcons of Kurdistan – claimed a mortar attack on Istanbul’s second largest airport Sabiha Gokcen on December 23 that killed one person.

The other major threat to Turkey’s security is Islamic State (IS). Turkey has become a target for the Islamist group after Ankara allowed the US-led coalition to use its basis for airstrikes against IS. Turkish jets have also launched few attacks on IS targets in Syria. Turkey hosts more than 2mn Syrian refugees.

Islamic State was held responsible for two suicide bomb attacks last year in Suruc, a town near the Syrian border, and in the capital Ankara, the latter killing more than 100 people at a peace rally.

The police in recent weeks have detained several suspected Islamic State members that officials say were planning attacks in Turkey. 

“The underlying concern here is this will further damage Turkey’s tourism sector already struggling with a somewhat disappointing season, and likely further buffeted by the Russian tourism ban”, said Tim Ash at Nomura International in an emailed comment on January 12.