A suicide bombing rocked a major shopping street in Istanbul today, killing four people and wounding 20 others just six days after a deadly attack in Ankara, Turkish authorities said. The attack took place on Istiklal Caddesi, a pedestrian street that was relatively quiet this morning but is usually thronged with shoppers, strollers and buskers later in the day. "This is a suicide attack, a terrorist attack," Istanbul governor Vasip Sahin told reporters at the scene, saying the bomber was also killed. Three of the wounded were in serious condition, he said. The bomb exploded near a shopping mall, but Sahin said the intended target was a local authority building in the Beyoglu neighbourhood, where Istiklal Caddesi is situated. The street, which adjoins Taksim Square in the European part of the city, was evacuated after the attack, an AFP journalist at the scene said. Armed police sealed off the area while a police helicopter hovered overhead. CCTV footage published online by Dogan news agency appeared to show the moment of the blast with a fireball erupting near a handful of passersby, sending them rushing for cover. Television images showed several ambulances ferrying the injured to hospital. Turkey, which has been rocked by five major bombings since July, had been on high alert for further attacks ahead of Kurdish New Year celebrations on Monday.

A Kurdish rebel group, the Kurdistan Freedom Falcons (TAK), claimed responsibility for an attack on March 13 on a busy transport hub in Ankara that killed 35 people. TAK, which also claimed a similar car bombing in Ankara in mid February that killed 29 people, has ties to the outlawed Kurdistan Workers' Party (PKK) against which the Turkish army is waging a major military campaign.

A court in Ankara yesterday evening remanded five people in custody on suspicion of links to last week's attack in the capital which was carried out by a 24-year-old female student named by TAK as Seher Cagla Demir.

In a statement, TAK said the bombing aimed to avenge Kurds killed during a ongoing military offensive against the PKK in the majority Kurdish southeast and said it had not meant to target civilians. Yesterday, Turkish airforce planes continued to bomb PKK hideouts in mountains across the border in northern Iraq, an army statement said.

During the week, the US embassy in Ankara had issued a warning to its citizens in Turkey to exercise caution ahead of the Kurdish Nevruz (New Year) celebrations, which have been a flashpoint for pro-Kurdish demonstrations in the past.

The Islamic State jihadist group was blamed for three other large-scale attacks in recent months, including a suicide attack in January in Istanbul in which 12 German tourists were killed and an attack on a peace rally in Ankara in October that claimed 103 lives.