Around 55 Iranian military personnel have been killed in Syria's civil war, Israeli intelligence believes, and a think-tank close to Israel's spy services said the toll is undermining support among Iranians for Iran's actions in Syria.While formally neutral on the four-year-old insurgency in the next-door Arab state, Israel has sought to raise alarm abroad about support given to Syrian President Bashar al-Assad by Israel's arch-foe Iran and Hezbollah guerrillas from Lebanon.With Russian forces also now weighing in on Assad's side, some Israeli media have carried unsourced reports presenting the de-facto axis between Moscow, Iran, Hezbollah and the Syrian army as plagued by poor coordination and battlefield losses.Speaking to Reuters, a senior Israeli military officer cited Israeli intelligence findings that "55-plus" Iranian personnel had been killed in clashes with Syrian rebels, in addition to a Hezbollah death toll he put at between 1,000 and 2,000.Tehran denies having any military forces in Syria, but says it has dispatched advisers to help Assad's army fight "terrorist groups." Hezbollah has not published a figure for its losses.Israel's Meir Amit Intelligence and Terrorism Information Center said in a report that 53 Iranians, including elite troops and senior officers, had been killed in Syria as of Nov. 15.The think-tank, which is located next to the headquarters of Israel's main foreign spy services and draws staff from them, said the Iranian public appeared to be increasingly questioning the wisdom of its actions in Syria.That has prompted Tehran to emphasize the importance of protecting Shi'ite Muslim shrines there from Sunni rebels and of shoring up Assad as a strategic asset, the think tank said."There are even demands to investigate the rising losses, suggesting the Iranian public regards with great skepticism the official Iranian claim that the Iranian presence in Syria is made up solely of 'advisers' and that Iranian forces are not actively involved in ground combat," its 54-page report said.Hossein Salami, deputy commander of the Iranian Revolutionary Guards Corps, last month sought to play down the force's losses."To give effective advice, the Revolutionary Guards advisers have to visit the front lines in Syria to become familiar with the reality of the battlefields," he told Iranian state TV."How could they help the Syrian army effectively by sitting in a room? The death toll of Iranians is not high."A regional security source who declined to be identified by name or nationality said that, at its peak, the Iranian force deployed in Syria was made up of 1,800 personnel but that number had since been reduced to 1,300.Iranian President Hassan Rouhani had called for the current deployment to be halved but was coming up against opposition from hardliners in the Iranian Revolutionary Guard Corps, the source added, declining to say where this information came from.