Unconfirmed reports from Syria say two Western journalists have been killed in the central city of Homs.Activists said an American and a French national had died after a shell hit a makeshift media centre in the Baba Amr area, which has come under bombardment.
Several other people were also killed and wounded, the activists added.
Opposition-held districts of Homs have been under siege by security forces for more than two weeks, with hundreds of people reportedly killed.
Activists said more than 40 died on Tuesday, including Rami al-Sayed, a man who broadcast a live video stream from Homs used by world media.
Mr Sayed was fatally wounded by shrapnel during the shelling of Baba Amr. His brother posted a video of his body in a makeshift hospital.
The French television journalist, Gilles Jacquier, was killed in Homs on 11 January, while visiting the city on a government-organised trip.
Some put Tuesday's death toll in the northern province of Idlib at more than 50.
New videos posted online by activists in Idlib suggest opponents of President Bashar al-Assad were the victims of summary executions.
One shows residents of the village of Abdita looking at a row of about a dozen dead bodies laid out on the ground.
There was similar footage from the nearby village of Balshun showing bodies scattered around in an open field.
Some had their hands bound and had died from a bullet wound to the head. Voices on the video said they had been summarily executed.
State media said security forces had been operating in the area, pursuing "armed terrorist gangs" and that a number had been killed.
In another video from Idlib, about 500 Syrian troops appear to announce their defection from the army, to join the rebel Free Syrian Army. The footage cannot be independently confirmed.