The Hezbollah flag. Israel estimates that the terror group has lost one third of its fighters in Syria. Photo: Wikimedia Commons.

Israeli officials estimate that one third of Hezbollah’s active fighters have been killed or wounded in the Syrian civil war, Israeli news site Walla reported on Tuesday.

According to the report, based on anonymous sources, between 1,300 and 1,500 Hezbollah fighters have been killed in combat in Syria, and an additional 5,000 have been wounded and are out of commission. Although Hezbollah — designated by the US and Israel as a terrorist group — is not open about its armed strength, some estimates say it could have up to 18,000 full-time and volunteers troops.

Hezbollah, long seen by Israelis as part of the Middle East axis also including Syria and Iran, has been fighting on behalf of Syrian President Bashar Assad and his backers in Tehran almost since the beginning of the armed conflict at the end of 2011.

The group has sent fighters to battle in the Syrian Golan region, near Israel, and has been heavily engaged in fighting around Al-Zabadani, a hill station near the Lebanese border.

Hezbollah-dominated civilian areas in Lebanon have been targeted by terrorists multiple times since the group started battling anti-government groups in Syria, including ISIS.

Israel has also carried out air strikes against Hezbollah targets, including weapons convoys from Syria, which it says is one of the red lines that, if crossed, would precipitate involvement in Syria.

Although as early as 2012, Hezbollah leaders were denying their role in fighting on behalf of Assad, Walla reported that Hezbollah has recently been very open about its casualties.

Arabic media recently reported that 14 Hezbollah fighters had died in combat against members of ISIS in the Beqaa Valley region of southern Lebanon, according to Walla. On Tuesday, Hezbollah-affiliated media reported that its fighters had killed an ISIS commander after detonating his convoy on the Syrian-Lebanese border, near the Qalamoun mountains.

Hezbollah has also boasted killing members of the Nusra Front, a group of anti-government Syrian fighters affiliated with al-Qaeda. Assad, whose brutal crackdown on anti-government forces has resulted in hundreds of thousands of casualties and a massive refugee crisis, insists he is battling terrorists.