Amateur video appears to show a Syrian military helicopter shot down by rebels in the city of Idlib.

A French official said in recent days - rebel forces have acquired heavy weapons - forcing the military to bomb rebel areas from the air.

Video obtained by Reuters purportedly shows a government fighter jet flying across Homs - and then an explosion - possibly caused by a bomb.

Meanwhile, others video appears to show rebels in intense gun battles on the ground ... and some armed with surface to air missiles.

(nat explosion)

Activists said more than 30,000 people have been killed in fighting since the uprising against President Bashir al-Assad erupted last March.

Meanwhile in Lebanon, international mediator Lakhdar Brahimi warned this civil war could spread across the Middle East.

SOUNDBITE: INTERNATIONAL MEDIATOR LAKHDAR BRAHIMI (Arabic):

"Those countries should realize as we have heard from officials today in Lebanon, that this crisis cannot remain within Syrian borders indefinitely. Either it will be addressed or it will overflow ... and be all-consuming."

Brahimi said - if Assad's forces called a ceasefire - the opposition forces would recognize it immediately.