Rebels downed a helicopter on Wednesday as troops fought to take back a key Syrian town, a watchdog said, as international peace envoy Lakhdar Brahimi warned the conflict risks setting the region ablaze.
Fighting for control of the Damascus-Aleppo highway raged around the northwestern town of Maaret al-Numan even as Brahimi appeared to have won tentative support for a ceasefire proposal.
Brahimi, the UN and Arab League envoy, warned of the conflict spreading in the Middle East as he visited neighbouring Lebanon, the latest leg of a regional tour aimed at ending more than 19 months of bloodshed.
"This crisis cannot remain confined within Syrian territory," the veteran troubleshooter told reporters in Beirut.
"Either it is solved, or it gets worse... and sets (the region) ablaze. A truce for (the Muslim holiday of) Eid al-Adha would be a microscopic step on the road to solving the Syria crisis."
Brahimi called this week for a temporary ceasefire in Syria during the four-day Eid al-Adha holiday starting on October 26.
"The Syrian people, on both sides, are burying some 100 people a day," he said on Wednesday.
"Can we not ask that this toll falls for this holiday? This will not be a happy holiday for the Syrians, but we should at least strive to make it less sad.
"If the Syrian government accepts, and I understand there is hope, and if the opposition accepts," a truce would be a step "towards a more global ceasefire," said Brahimi.
The Syrian conflict began in March 2011 with pro-reform protests inspired by the Arab Spring uprisings.
It has since transformed into a civil war pitting mainly Sunni rebels against President Bashar al-Assad's regime, which is dominated by his minority Alawite sect, an offshoot of Shiite Islam.
At times it has also spilled over into neighbouring countries, including Lebanon and Turkey.
Tensions have soared between Turkey and Syria with Ankara taking an increasingly strident line towards its southern neighbour since a shell fired from inside Syria killed five Turks on October 3.
Brahimi has been promoting the idea of a ceasefire during Eid al-Adha on the tour that has included stops in Sunni-ruled Egypt, Turkey and Saudi Arabia, as well as Shiite-led Iran and Iraq.