Al Jazeera says one of its reporters has been shot dead by a government sniper in the Syrian province of Daraa - the second reporter to be killed by snipers in 24 hours in strife-torn Syria.

"Mohammed Hourani was shot dead by a regime sniper in Basra al-Harir in the province of Daraa, while he was covering the clashes there," the Qatar-based satellite news channel said in a statement.

The 33-year-old Syrian journalist was described by his employer as "courageous and accurate" in his reporting.

Before joining Al Jazeera, Hourani was an activist in the uprising against president Bashar al-Assad, the broadcaster said.

Outspoken in its support for the revolt against the Assad regime, Al Jazeera vowed to pursue its editorial line despite the latest killing.

Amateur video posted online and distributed by activists showed the moment that Hourani was killed.

Wearing a beige jumper and carrying a microphone embossed with Al Jazeera's logo, he stood in a line of rebel fighters running one by one across a muddy alley, ducking as they sped to avoid being shot by snipers positioned nearby.

Hourani was hit as a sniper fired at least three shots, and fell to the ground.

His death comes a day after Belgian-born French journalist Yves Debay was killed by a sniper in the city of Aleppo.

"He was killed on one of Aleppo's fronts," said the Aleppo Media Centre, adding he was "shot by a regime sniper".

Debay founded Assaut magazine, a French publication specialised in defence.

The killings take the death toll of reporters who have died in Syria's 22-month conflict to at least 20, according to a count by AFP and Paris-based media watchdog Reporters Without Borders (RSF).

"We condemn the growing threats to journalists, who are often being targeted," RSF chief Christophe Deloire said in a statement.

"Syria is now the world's most dangerous country for news providers of all kinds."

ABC/AFP