BEIRUT - Syrian rebels cast doubt on Monday on prospects for a temporary truce aimed at stemming bloodshed in the 19-month-old conflict, saying it was not clear how an informal ceasefire this week could be implemented.International mediator Lakhdar Brahimi, who held talks in Damascus on Sunday with Syrian President Bashar Assad, has proposed Assad's forces and the rebels hold fire during the three-day Islamic holiday of Eid al-Adha which starts on Friday.Jordanian soldier killedSyria's conflict has spilled over into its neighbors in recent weeks. The army has exchanged cross-border fire with Turkey, a Lebanese intelligence chief whose investigations implicated Syrian officials was assassinated on Friday and a Jordanian soldier was killed near the border overnight.Information Minister Samih Maaytah said the soldier, who died in clashes with Islamist fighters trying to cross into Syria, was the first to die on the Syrian border since the uprising erupted against Assad last year.Brahimi declined to say how Assad had responded to his ceasefire appeal. After his talks with the president he said the idea had won wide support among rebels and the political opposition, but suggested it was up to individual groups to decide how to implement it."Everyone can start this when they want, today or tomorrow for example, for the period of the Eid and beyond," he told reporters.Syria has not publicly embraced Brahimi's proposal and state media quoted Assad as telling him that any initiative must be centered around "halting terrorism and ... commitment by the countries involved in supporting, arming and harboring the terrorists in Syria to stop these actions".Syrian authorities blame neighboring Turkey in particular for the bloodshed because it has sheltered mainly Sunni Muslim rebels fighting to overthrow Assad, from Syria's Alawite minority which is an offshoot of Shi'ite Islam. Gulf Sunni powers Saudi Arabia and Qatar also support arming the rebels."The indications that are now apparent and the government's reaction...do not show any signs of a real desire to implement this ceasefire," said Ahmed Ben Hilli, deputy secretary-general of the Arab League."We are days away from Eid. We hope the situation changes and the government and opposition respond even a little bit to this door for negotiations," he said on the sidelines of a conference in Dubai.Iran's Deputy Foreign Minister Hossein Ami-Abdollahian called for both sides to establish a lasting ceasefire, and said the two sides in the conflict were beginning to converge."The views of different sides are getting closer to each other and they have reached the conclusion that they should consider a political solution in Syria," Abdollahian said after talks with his Russian counterpart Mikhail Bogdanov. His comments might reflect the growing concerns of outside powers at the relentless bloodshed but on the ground both parties to the armed conflict appear committed to a military solution.The Syrian Observatory said there were heavy clashes in towns around Damascus such as Harasta, Douma and Artouz, and said helicopter gunships fired rockets on a village in the northern province of Idlib.Rebel fighters also attacked a military base at Wadi al-Deif, close to the town of Maarat al-Numan which they seized earlier this month, cutting the country's main north-south highway linking Damascus and Aleppo.His call has won the backing of international powers on both sides of the crisis including Iran and Russia, which have provided support to Assad, and Turkey, which backs the rebels in a conflict that has killed 30,000 people.But neither Syria's army nor the rebels have shown signs of easing off as Eid nears. More than 200 people were killed on Sunday in fighting and bombardments including 60 soldiers, the Syrian Observatory for Human Rights said.On Monday the British-based group reported army shelling in Deir al-Zor in the east and Deraa in the south, as well as heavy clashes in towns and suburbs around the capital Damascus."This truce is just a media bubble. Who is going to implement it and who is going to supervise it?" said Colonel Qassem Saadeddine, a former army officer who defected and is now head of a rebel military council in Homs province."We are still committed to any UN decision. But on this truce...what is the mechanism to implement it?" Saadeddine, who is also spokesman of the joint command of the Free Syrian Army inside Syria, told Reuters.He said rebels had implemented the last ceasefire in Syria - an April 12 deal brokered by former mediator Kofi Annan - but that Assad's forces had not honored it. Syrian authorities say it was they who implemented and rebels who broke the ceasefire.Another rebel commander in Damascus, who declined to be named, was more blunt: "The truce will not happen. We will not accept it. It's not in our interest," he said, adding that a three-day truce would achieve little anyway.