US warns of 'Starbucks attack risk' in south Turkey

The United States has warned of the risk of a terror attack in the southern Turkish city of Gaziantep close to the Syrian border on businesses frequented by Westerners, including the popular coffee chain Starbucks.

The US embassy in Ankara said in a message to citizens that there are reports of a police investigation into a "terror cell" in Gaziantep, which in August was hit by a deadly suicide bombing on a wedding blamed on Islamic State (IS) extremists.

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It said the information suggests the extremists are "possibly targeting" shopping centres, Starbucks, the popular upscale Turkish restaurant chain Big Chef or other businesses frequented by Western customers.

"US citizens in Gaziantep are advised to exercise caution when patronising these sorts of businesses and to avoid them if possible," it said in the notice published late Wednesday.

A major city lying just 60 kilometres (37 miles) north of the Syrian border, Gaziantep has become a hub for Syrians fleeing the civil war in their country.

The Turkish authorities have acknowledged that Islamic State extremists had built up a presence in the city with the aim of staging attacks.

But the US embassy did not specify which group was suspected of planning to carry out the attacks.

Turkey has suffered a string of attacks in the last 12 months in Ankara, Istanbul and elsewhere blamed on Kurdish militants and Islamic State.

In June, 47 people were killed in a triple suicide bombing and gun attack at Istanbul's Ataturk airport, with authorities pointing the finger at Islamic State.

Fifty four people were killed in the August 20 suicide bombing on a Kurdish wedding in Gaziantep that President Recep Tayyip Erdogan said was carried out by a child bomber acting on the orders of Islamic State.

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Embassies are also on a high state of alert after a man wielding a knife tried to attack the Israeli embassy in Ankara on Wednesday, while the British embassy was closed last Friday for security reasons.

Separately, the official Anadolu news agency reported that 16 people were detained early Thursday on suspicion of membership of Islamic State, in the latest of a series of raids in Istanbul.

It said that there was intelligence some could have been planning attacks in the city and some had also taken part in the conflict in Syria.