Five people including a suicide bomber were killed and 36 wounded in an attack on a major shopping and tourist district in central Istanbul on Saturday, in the fourth suicide bombing to hit Turkey this year.

There was no immediate claim of responsibility for the attack on part of Istiklal Street, a long pedestrian street lined with global shops and foreign consulates, a few hundred metres from an area where police buses are often parked.

Two Turkish officials told Reuters evidence suggested the attacker was likely from the outlawed Kurdistan Workers Party (PKK) or the Islamic State militant group.

Nato member Turkey faces security threats from both the PKK in the mainly Kurdish southeast and has also been a target for Islamist militants.

One of the official said the bomber had planned to hit a more crowded spot.

"The attacker detonated the bomb before reaching the targeted point because they were scared of the police," the official said, declining to be named because the investigation is ongoing.

Armed police sealed off the shopping street where half a dozen ambulances had gathered. Forensic teams in white suits scoured the area for evidence. Police helicopters buzzed overhead and panicked shoppers fled the area, ducking down narrow sidestreets.

"My local shopkeeper told me someone had blown himself up and I walked towards the end of the street," one neighbourhood resident told Reuters.

"I saw a body on the street. No one was treating him but then I saw someone who appeared to be a regular citizen trying to do something to the body. That was enough for me and I turned and went back."

Istiklal Street, usually thronged with shoppers on weekends, was quieter than normal before the blast as more people are staying home after a series of deadly bombings.

Health Minister Mehmet Muezzinoglu confirmed that 36 people had been wounded and seven of those were in serious condition. Twelve of the wounded were foreigners, he said.

Israel's foreign ministry confirmed some of its citizens were among the wounded.

Broadcaster NTV said six of the wounded were Israeli tourists and two others were from Iceland.

"We as a nation are unfortunately now face to face with a situation of unlimited, immeasurable acts that are inhumane, defy human values and are treacherous," Muezzinoglu said.

A suicide car bombing in the capital Ankara killed 37 people this month. A similar bombing in Ankara last month killed 29 people. A Kurdish militant group has claimed responsibility for both of those bombings.

In January, a suicide bomber killed around 10 people, most of them German tourists, in Istanbul's historic heart, an attack the government blamed on Islamic State.

The attack brought swift condemnation from around the globe. Iranian Foreign Minister Mohammad Javad Zarif, who was on an official visit to Istanbul, described the bombing as an attack that showed "the ugly face of terrorism".

France condemned the attack as "despicable and cowardly".

Germany, which this week shut its embassy, consulate and schools in Ankara and Istanbul over security fears, urged tourists in Istanbul to stay in their hotels.

Turkey's Peoples' Democratic Party (HDP), a Kurdish-rooted opposition party, condemned the bombing.

"Just as in the Ankara attack, this is a terrorist act that directly targets civilians," the HDP said in an e-mailed statement. "Whoever carried out this attack, it is unacceptable and inexcusable."

Turkey is fighting Islamic State in neighbouring Syria and Iraq. It is also battling PKK militants in its southeast, where a 2-1/2-year ceasefire collapsed last July, triggering the worst violence since the 1990s.

In its armed campaign in Turkey, the PKK has historically struck directly at the security forces and says that it does not target civilians. However, the recent bombings suggest it could be shifting tactics.

The PKK is looking to carry out attacks aggressively during the Newroz spring holiday around March 21, the official said. Newroz is largely celebrated by Kurds in Turkey and has in past years seen violent clashes between demonstrators and the security forces.-Reuters