A Syrian refugee girl holds pictures of Syria’s President Bashar Assad and Lebanon’s Hizbullah leader Hassan Nasrallah, southern Lebanon, on March 18.

BEIRUT — Lebanon’s Hizbullah militia chief said his fighters’ intervention in Syria had kept an al-Qaeda splinter group that has seized territory in Iraq from spreading west into Lebanon.

Hizbullah has provided significant help to Syrian President Bashar al-Assad in retaking some territory from rebels bent on ousting him. In the process, Hizbullah men have often clashed with Islamic State in Iraq and al-Sham (ISIS) rebels, who formally broke with al-Qaeda in February and have since made rapid gains in Syria and Iraq.

ISIS, which aims to establish a caliphate based on medieval Islamic principles and spanning the two countries, stunned Iraqi leaders when it overran Iraq’s second-largest city Mosul last week, then thrust south to the fringes of Baghdad.

Hezbollah chief Hassan Nasrallah was quoted by Lebanese newspaper Al-Safir as telling a meeting of party backers that ISIS could have spread to Lebanon if Hizbullah had not stepped in.

“If we had not intervened in Syria at the appropriate time and in the appropriate way … ISIS would now be in Beirut,” he said.

Nasrallah praised calls by Shi’a clerics in Iraq for volunteers to take up arms against ISIS, whose swift advance through majority Sunni areas of northern Iraq threatens civil war and a possible break-up of the country. 

“The aim of this (call) was not to protect a specific sect, but to protect all of Iraq,” Nasrallah said.

Opponents of Hizbullah’s intervention in Syria say it has dragged Lebanon further into its civil war, worsened sectarian tensions in Lebanon and marked a departure from Hizbullah’s founding mission of confronting Israel.

But members of Lebanon’s Shi’a community have also been alarmed by the rise of radical Sunni jihadists in Syria.

Militants have hit Shi’a targets in Lebanon with car bomb attacks, although those have stopped since Hezbollah and Syrian government forces ousted rebels from a series of towns and villages near the Lebanese border in March and April.

Hizbullah and Assad are both backed by Iran, while Sunni Gulf Arab monarchies have backed insurgents in Syria.