Rebels downed a helicopter in fierce fighting Wednesday with troops seeking to retake a key Syrian town, a watchdog said, as peace envoy Lakhdar Brahimi warned the conflict risks setting the region ablaze. The battle for 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 plan. The UN and Arab League envoy warned of the conflict spreading as he visited neighbouring Lebanon, the latest leg of a Middle East 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 during the four-day Eid 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\". Arab League chief Nabil al-Arabi, who met Brahimi on Tuesday, backed the proposal. He urged \"the Syrian government and armed Syrian opposition to respond to calls for a truce and stop violence and military action during the days of Eid,\" also asking for international support. The conflict began in March 2011 with pro-reform protests inspired by the Arab Spring uprisings. It has since become a civil war pitting mainly Sunni rebels against President Bashar al-Assad\'s regime 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\'s spokesman Ahmad Fawzi told AFP the envoy would \"soon go to Damascus.\" His tour has already taken him to Sunni-ruled Egypt, Turkey and Saudi Arabia, as well as Shiite-led Iran and Iraq. Damascus says it is prepared to discuss the truce proposal with Brahimi while the exiled opposition says it would welcome any ceasefire but insists the ball is in the government\'s court to halt its daily bombardments. \"The Syrian side is interested in exploring this option and we are looking forward to talking to Mr Brahimi,\" Syrian foreign ministry spokesman Jihad Maqdisi told AFP. The opposition Syrian National Council said it expected the rebel Free Syrian Army to reciprocate any halt to the violence but the government had to act first. \"We would welcome any halt to the killings but we think the appeal needs to be addressed first to the Syrian regime, which has not stopped bombarding Syrian towns and villages,\" SNC leader Abdel Basset Sayda told AFP. On the battlefront, rebels shot down a helicopter gunship in the northwest as the army fought to recapture the strategic town of Maaret al-Numan, said the Syrian Observatory for Human Rights. Warplanes targeted a rebel blockade of a highway in Idlib province which has halted the regime\'s efforts to reinforce Aleppo, theatre of intense fighting for three months. The early morning air raids targeted Maaret al-Numan and nearby villages, which fell to the rebels a week ago as they pushed to create a \"buffer zone\" abutting Turkey, said the Observatory. The fighting flared as rebels attacked a convoy of government tanks in the town of Maarhtat as it headed for Wadi Deif army base, the largest in the area. Violence across Syria killed at least 28 people on Wednesday, according to a preliminary Observatory toll. A baby was killed in Douma, an opposition bastion near Damascus targeted by regime shelling, and troops stormed the town of Jusseih in the central province of Homs after bombarding it for days. The Observatory -- which relies on a network of activists, medics and lawyers for its information -- says some 33,000 people have been killed in the uprising, among them 2,300 children.