The early-morning strike on a Syrian regime air base in central Homs province has killed at least 14 fighters, including allied Iranian forces, the Syrian Observatory for Human Rights says.
Damascus on Monday accused Israel of carrying out deadly bombing raids on a military air base in the country's centre, the SANA news agency reported.
The strike came after US President Donald Trump on Sunday warned of a "big price to pay" following a suspected chemical attack that killed at least 42 people in the eastern suburbs of Damascus, the last foothold of anti-regime Syrian rebels in the area.
"The Israeli attack on the T-4 airport was carried out with F-15 aircraft that fired several missiles from above Lebanese territory," SANA said, citing a military source.
SANA said regime air defences had shot down eight missiles.
A war monitor said the early-morning strike on the air base in central Homs province killed 14 fighters, including allied Iranian forces.
TRT World's Abubakr al Shamahi has more.
No comment from Israel
When asked about the assault, an Israeli spokeswoman declined to comment.
Israel has struck Syrian army locations many times in the course of the conflict, hitting convoys and bases of Iranian-backed militias that support Bashar al Assad's forces.
Defence analysts say there are large deployments of Russian forces at the base, and jets fly regular sorties from there to strike rebel-held areas.
US, France not involved
An earlier report on SANA said the Homs attack was "likely to be an American aggression."
A spokesman for the Pentagon, Christopher Sherwood, ruled out US involvement.
"At this time, the Department of Defense is not conducting air strikes in Syria," the Pentagon said in a statement.
"However, we continue to closely watch the situation and support the ongoing diplomatic efforts to hold those who use chemical weapons, in Syria and otherwise, accountable."
France also said on Monday it was not involved in the overnight attacks.
Many dead, including women and children, in mindless CHEMICAL attack in Syria. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world. President Putin, Russia and Iran are responsible for backing Animal Assad. Big price...— Donald J. Trump (@realDonaldTrump) April 8, 2018
Suspected chemical attack in Douma
The Syrian opposition blames the suspected chemical attack on Saturday in the town of Douma on regime forces.
As international officials worked to try to confirm the chemical attack, Trump took the rare step of directly criticising Russian President Vladimir Putin in connection with the incident.
The Syrian regime denied its forces had launched any chemical assault. Russia, Assad's most powerful ally, called the reports fake.
The Russian foreign ministry warned against military action on the basis of "invented and fabricated excuses."
For those who spread another fake news about alleged use of chemical weapons in #Douma on April 7.We repeatedly warned that a provocation of this kind with the help of #WhiteHelmets is being prepared by besieged terrorists and there sponsors.And ask yourself a simple question:— Dmitry Polyanskiy (@Dpol_un) April 8, 2018
..why do Syrian forces who have military initiative and will soon completely free #Douma need to use CW, even if they had it, which Damascus denied? No logic!On the contrary,terrorists have all the reasons to stage such a provocation to attract attention. Dirty methods,as before!— Dmitry Polyanskiy (@Dpol_un) April 8, 2018
The suspected chemical attack came as the Syrian regime on Friday intensified the air and ground assault on Douma, the last rebel foothold in eastern Ghouta district on the edge of the capital, Damascus.
The UN Security Council will meet twice on Monday following rival requests by Russia and the United States to investigate the alleged chemical attack.
TRT World's Kevin McAleese has more.
'Strong, joint response' to Syria
French President Emmanuel Macron spoke to Trump by telephone and the two agreed that they would work together to establish clear responsibility for what Macron's office said they had agreed was a confirmed chemical attack.
Macron said in February “France will strike” in the event of lethal chemical weapon attack on civilians by regime forces in Syria.
The medical relief organisation Syrian American Medical Society (SAMS) and the civil defence service, which operates in rebel-held areas, said in a joint statement 49 people had been killed in the attack.
Ambassador Nikki Haley on the #chemicalweapons attack in #Syria: “The Security Council has to come together and demand immediate access for first responders, support an independent investigation into what happened, and hold accountable those responsible for this atrocious act.” pic.twitter.com/hjizx5pM7r— US Mission to the UN (@USUN) April 8, 2018
A pattern of chemical attacks
One video shared by activists showed bodies of about a dozen children, women and men, some with foam at the mouth. "Douma city, April 7 ... there is a strong smell here," a voice can be heard saying.
These reports could not be independently verified.
The United States launched a cruise missile strike on a Syrian air base a year ago in response to the killing of dozens of civilians in a sarin gas attack on the opposition-held town of Khan Shaykhun in northwest Syria. The gas attack was blamed on Assad.
US government sources say Washington's assessment of Saturday attack was that chemical weapons were used.
The EU also said evidence pointed to the use of chemical weapons by Assad's forces.
A European diplomat said Western allies would work on building a dossier based on photos, videos, witness testimony and satellite images of Syrian flights and helicopters. However gaining access to samples on the ground would be difficult.
UN war crimes investigators had previously documented 33 chemical attacks in Syria, attributing 27 to the Assad regime, which has repeatedly denied using the weapons.
This is a developing story.