A Syrian journalist who was shot in the Turkish city of Gaziantep in an attack claimed by the Islamic State of Iraq and the Levant (ISIL) has died from his wounds, a close friend said.

The death of Halab Today TV presenter Mohammed Zahir al-Sherqat on Tuesday marks the fourth assassination of a Syrian journalist in Turkey that has been claimed by ISIL, also known as ISIS.

Sherqat, who was shot in the neck from close range on Sunday while out walking, died in a hospital in Gaziantep near the Syrian border, according to his friend Barry Abdulattif, a Syrian activist.

Friends told the Associated Press news agency that the journalist had received death threats as recently as two months ago from ISIL.

The group took responsibility for the attack on Monday via their Amaq news agency, which said Sherqat "used to present anti-Islamic State programmes".

The journalist came to Turkey in 2015 after surviving an assassination attempt in Syria and started to work with Halab Today. His programmes took a stance against ISIL and other groups.

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Sherqat, a native of the Syrian town of Al-Bab, was an imam who studied Islamic Law at Damascus University, Abdulattif said.

When the Syrian revolution started in 2011, he was a founding member of the local coordinating committee of al-Bab and a field organiser of demonstrations against the Syrian government.

He later formed the Abu Bakr al-Sadiq Brigade which fought under the banner of the opposition Free Syrian Army.

When groups such as al-Nusra Front and ISIL appeared in al-Bab, Sherqat opposed them, according to Abdulattif, who is also a native of the town.

The killing of Sherqat follows the assassinations last year of two Syrian journalists who were found with their throats slit in the southeastern city of Sanliurfa and a third journalist who was shot dead in the street in Gaziantep.

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The attacks have prompted media pressure group Reporters Without Borders to urge Turkish authorities to protect exiled Syrian journalists in the country.

"The situation is very bad, we don't feel safe," Abulattif said. "We know there are a lot of sleeper [ISIL] cells in Turkey and elsewhere but it is not easy to catch them."

Many Syrian activists based in Gaziantep or other cities near the border report receiving threats from ISIL, yet most do not have a financially viable or legal way out of Turkey.

Complicating matters, a controversial deal between Europe and Turkey, home to 2.7 million Syrians, recently came into effect with the aim of curbing the flow of people to Europe.

Turkish authorities haven't commented on the murder of Sherqat.