IS group chief suspect in Istanbul airport attack

Tuesday's suicide attack on passengers at Istanbul's Ataturk airport bears the "hallmark" of the Islamic State group, CIA Director John Brennan said on Wednesday.

At least 41 people were killed and 239 more injured when militants stormed the airport detonating bomb belts among travellers.

Although IS has not claimed responsibility for the attack, the CIA head believes the group was behind the killings.

"The despicable attacks in Istanbul International Airport yesterday that killed dozens and injured many more certainly bears the hallmark of [IS'] depravity," Brennan said.

The attack appeared to be well coordinated and ruthless. Militants fired indiscriminately into crowds of passengers before blowing themselves up at the entrance of the airport, one of the busiest flight hubs in Europe.

Brennan believes that such an attack could be planned for US airports.

"If anyone believes that the US homeland is hermetically sealed... I would guard against that," he said.

Turkish authorities have said that IS or a far-left Kurdish rebel group known as the Kurdistan Freedom Falcons are the most likely culprits.

Both militant groups have carried out attacks in Turkey, but the scale of the violence in the most recent killings has led some Turkish officials to blame the Syria and Iraq-based jihadi group.

Interior Minister Efkan Ala said there was an ongoing "serious and comprehensive investigation" into the attack "[but] first signs point to [IS] but it's not certain yet".

Anaylsts also believe the jihadi group carried out the attack.

Ege Seckin, an analyst at IHS Country risk, said the attack was "most likely conducted by the Islamic State to undermine the Turkish economy by attacking the airport ahead of the summer months, when tourism peaks".

Turkey's economy is heavily reliant on tourism, and with the summer holiday season beginning this attack and others like it will be deep a blow for the country, which is deperate to ramp up economic growth.