A suicide bomb attack at a busy shopping area in the Turkish city of Istanbul has killed at least four people, officials say.

Another 36 were injured – 12 foreign nationals – as the bomb went off near a government building on Istiklal Street.

No-one has admitted carrying out the attack, the latest to target Turkey in recent months.

The Turkish government has blamed Kurdish militants for previous attacks and has retaliated against them.

Saturday’s attack in Istanbul – Turkey’s largest city – occurred at about 11:00 local time (09:00 GMT).

Uwes Shehadeh was some 500m (1,640ft) away when he heard “a horrific and horrible noise”.

“People didn’t know what was going on. It was very chaotic. Everyone was screaming and running away,” he told the BBC.

“Istanbul is on high alert and people are very worried as to what will happen next.”

Among the foreigners injured were: six Israelis, two Irish citizens, and one national from Germany, Iceland, Dubai and Iran.

Medics try to help wounded people after an explosion in Istiklal Street in IstanbulMedics rushed to try to help a wounded man
Turkish police, forensics and emergency services, work at the blast scene.Turkish police, forensics and emergency services work at the blast scene
Injured being taken awaySome people are in a serious condition, officials say
Turkish police push people away after an explosion on the pedestrian Istiklal street in Istanbul, 19 March 2016.Police quickly cordoned off the area

Both the so-called Islamic State (IS) and Kurdish militants have claimed recent attacks in Turkey.

President Recep Tayyip Erdogan has said terror groups are targeting civilians because they are losing their struggle against Turkish security forces.

Turkey is part of the US-led coalition against IS and allows coalition planes to use its air base at Incirlik for raids on Iraq and Syria.