Video posted to a social media website purports to show heavy shelling in Homs - a city that has become the bloody epicentre of a year-long revolt against Syrian President Bashar al-Assad's government.
The video upload date is shown as the 7th of April, but a male voice is heard describing the shelling as taking place on April 8.
Reuters is unable to independently verify the content of this footage.
Opposition activists say 74 civilians have been killed in a country-wide offensive by Syrian troops ahead of next week's U.N.-backed ceasefire.
At least 15 rebels and 17 security force members were also killed.
Each side has accused the other of intensifying assaults before the truce.
International mediator Kofi Annan says there's been an "unacceptable" escalation in violence.
He's called on the Syrian government to keep to pledges to end the bloodshed before Tuesday's deadline.
Syria says it wants "written guarantees" from insurgents that they will stop fighting, before it pulls troops back.
According to the U.N., more than 9,000 people have been killed since security forces unleashed a crackdown on rebels and civilians just over a year ago.
Travis Brecher, Reuters