Istanbul bombing: Explosion outside Turkish police station hours after Isis suicide bomber targets border crossing

Bombing is latest in series of attacks by Isis and Kurdish militant groups

Police special forces near the scene of the blast in Istanbul (Reuters)

A large explosion has struck outside a police station in Istanbul just hours after an Isis suicide bomber killed more than 20 people near a refugee camp on the Syrian border.

Vasip Şahin, the governor of Istanbul, said a motorbike bomb was source of the blast in the Turkish city's Yenibosna district on Thursday afternoon.

A witness in a nearby school told the Daily Sabah newspaper gunshots were heard after the explosion, while another at a bus station 500 metres away felt the ground shake with the force of the blast.

At least 10 people were injured, with photographs of the scene showing the road strewn with debris and several cars and vans with their windows smashed and bodywork dented by shrapnel.

Mr Şahin said the attack struck Fatih Street, which leads to a mosque along an avenue of busy shops and cafes.

There was no immediate claim of responsibility from militant groups.

The attack in Istanbul came just hours after at least 29 people were killed in a suicide bombing near a refugee camp at the Syrian border.

Isis claimed responsibility for the attack, which killed several Turkish-backed members of the Free Syrian Army, who are fighting both Isis and Kurdish rebels in the country's civil war.

Activists said the opposition fighters had gathered near a small restaurant in Atmeh, which houses a border crossing used by anti-government rebels to transport both fighters and supplies.

Graphic footage of the aftermath of the blast showed about 18 bodies lying on the ground outside what appears to be a clinic, including some wearing military uniforms.

Numan Kurtulmus, Turkey's deputy Prime Minister, described the blast as an “inhuman attack”, adding that “those who perpetrated this committed a crime against humanity”.

Turkey has been the target of a string of massacres by both Isis and Kurdish separatists in recent months.

Islamists have attacked tourists and protestsers in Istanbul and Ankara, as well as launching suicide bombings in areas near the Syrian border.

Kurdish militant groups have more frequently targeted police and the Turkish armed forces, who are currently carrying out operations against the separatist Kurdistan Workers' Party (PKK) in the south-east as a three-decade insurgency continues.

Another group, the Kurdistan Freedom Falcons (TAK) have also claimed responsibility for attacks including a car bombing that killed 37 people in Ankara in March.