Fighters linked to al-Qaeda have kidnapped and executed an Iraqi freelance cameraman working in northern Syria, the first foreign journalist killed by fighters in the rebel-held north, according to a press freedom watchdog.

The Paris-based Reporters Without Borders said the al-Qaeda affiliated Islamic State of Iraq and the Levant (ISIL) seized Yasser Faysal al-Joumaili on Thursday while he was on a reporting trip in northern Syria's Idlib province on December 4.

"Joumaili had been working as a freelance cameraman for an unidentified Spanish media outlet in strife-torn Aleppo province for about 10 days" said Soazig Dollet, head of Reporters Without Borders (RSF) for the Middle East and North Africa desk.

He was kidnapped by fighters of the Islamic State of Iraq and the Levant (ISIL) while on his way out of Syria and executed in the northwestern border province of Idlib on Wednesday, she added.

The Syrian Observatory for Human Rights said Joumaili was stopped at a checkpoint by three armed men who then shot him.

The Baghdad-based Journalistic Freedoms Observatory (JFO) said Turkish officials were not allowing Joumaili's body to be brought out of Syria.

"The family of Joumaili told JFO that the body of their son was stuck at the Bab al-Hawa border crossing with Turkey and Turkish authorities were preventing it from passing," the group said.

It said Joumaili was 34 and married with three children.

He was from the city of Fallujah, west of Baghdad, a key battleground in the insurgency that followed the US-led invasion of Iraq in 2003, and had done work for Al Jazeera International and the Reuters news agency.

In recent months, ISIL has kidnapped dozens of Syrian activists and news providers, as well as several foreign journalists.

The group, which has its roots in al-Qaeda's Iraq affiliate, was accused of assassinating Syrian reporter Mohammad Saeed, who worked for Al-Arabiya news channel, in his native Aleppo province in late October.

According to Paris-based Repoters Without Borders, Joumaili was the eighth foreign journalist to have been killed in Syria since the conflict erupted in March 2011.

Twelve Syrian professional journalists and at least 91 citizen journalists have also been killed.