Iraq militia vows 'appropriate response' for deadly Syria airstrike

Iraq's Hizballah Brigades militia vowed on Thursday to exact revenge for a deadly air raid earlier this week on its fighters in Syria, blaming the US or Israel for the attack.

The militia said 22 of its fighters were killed in Sunday's airstrike on a military base in eastern Syria that reportedly killed more than 50 people.

Both Damascus and the Hizballah Brigades at first pointed the finger at the US-led coalition fighting the Islamic State group in the area. 

But a US official said there was cause to believe Israel carried out the deadly raid along the border with Iraq that hit forces battling on the side of Syrian President Bashar al-Assad.

Hizballah Brigades spokesman Jaafar al-Husseini said it was still too early to say definitively whose forces carried out the strike, but insisted it "could only have been" the Americans or Israelis.

"When it becomes known who was responsible then there will be an appropriate response and the hand of the resistance will strike anywhere," he said during a memorial ceremony for the dead at a Baghdad mosque.

Israel has pledged repeatedly to do whatever it takes to stop Tehran or its "proxies" from building up their military presence in Syria and carried out large-scale strikes last month in the war-torn country.

But the country maintains a policy of not commenting on specific strikes or raids.

The Shia Hizballah Brigades are part of the Hashed al-Shaabi paramilitary units that battled IS in Iraq under the command of Prime Minister Haider al-Abadi.

The group has also been fighting for Assad across the border in Syria independent of the authorities in Baghdad.

Iraq declared victory over IS in December of last year but the group still controls pockets of territory in Syria, where they are facing both US-supported forces and pro-regime troops.

A "de-confliction line" exists in eastern Syria to keep the rival forces confronting IS from coming into conflict with each other.

The buffer has largely been successful in keeping the two offensives apart, but there have been exceptions.

The deadliest incident was in February, when US-led coalition air strikes killed at least 100 pro-regime fighters in Deir az-Zour province, including Russians.

Sunday's strike hit a site that sits on a key route linking the Syrian-Iraqi border, and Iran beyond that, all the way west to the frontier with Lebanon.

Agencies contributed to this report. 

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