Eight senior Iranian military officers have been killed in war-torn Syria -- where Iran supports the embattled regime of Syrian President Bashar al-Assad -- since 2013, including three generals killed this week.

On Oct. 9, Hossein Hamadani, a senior commander of Iran's Revolutionary Guards, was reportedly killed by the ISIS group in Aleppo, according to Iranian media.

Three days later, Major-General Farshad Hasunizade and Brigadier General Hamid Mohtarband -- also from Iran's Revolutionary Guards -- were also killed in Syria.

Lebanon's Shia Hezbollah militia, meanwhile, lost two senior commanders in Syria's Hama province last week.

Since 2013, Iran has lost senior commanders in Syria's Damascus, Aleppo, Qunaitera and Hama provinces, according to Iranian media.

At least 250,000 people have been killed since the Syria conflict began in early 2011, with 7.6 million internally displaced and over four million having fled to nearby countries.