Iran says 7 dead in Syria strike will 'not go unanswered'

At least four Iranian military advisers were killed in an Israeli airstrike on Syria's T4 airbase, east of Homs, on Monday morning, it has been reported.

According to independent monitors, hundreds of thousands of civilians have been killed in the war, mostly by the regime and its powerful allies, and millions have been displaced both inside and outside of Syria.

But Israeli officials said the Tiyas, or T-4, air base was being used by troops from Iran and that Israel would not accept such a presence in Syria by its arch foe.

In Damascus, Ali Akbar Velayati, the diplomatic advisor to Iran's supreme leader, Ayatollah Ali Khamenei, issued an open threat to Israel on Tuesday after the Iranian government said it had lost seven personnel in the strike.

"We will stand by Syria's government against any foreign aggression", Velayati said, adding that Tehran backs Damascus in its fight against the United States and Israel.

US President Donald Trump's statement about Tehran's possible involvement in the alleged chemical weapons attack in the Syrian town of Douma is hypocritical, Iranian Foreign Minister Mohammad Javad Zarif wrote on Twitter on Tuesday.

"Israel will not allow Iranian entrenchment in Syria".

Russian Foreign Minister Sergei Lavrov called the strike on the base a "very risky development".

Israel carried out strikes against a Syrian government base in the country's centre in February, with the Observatory identifying it at the time as T-4.

Iran and Russian Federation are allies of Assad, with Iran evidencing some control over Syrian military installations. Israeli officials refused to comment on the strike. While Assad and his allies deny perpetrating chemical weapons attacks, the global community continues to collect damning evidence.

The news agency also quoted Qasemi as saying that the reports of the gas attack "do not match facts".

Israel is believed to have carried out numerous raids inside Syria since 2013, targeting the regime and the Lebanon-based terror group Hezbollah, which is backed by Iran.