The wreckage of a building described as part of the Scientific Studies and Research Center compound north of Damascus, Syria, is seen during a media tour organized by the government in April. (Louai Beshara/AFP/Getty Images)

Syria on Tuesday accused Israel of assassinating a top Syrian rocket scientist over the weekend, heightening the growing tensions between the two countries as Syrian government troops restore control over areas close to Israel.

Aziz Asbar, a research director at Syria’s Scientific Studies and Research Center, was killed Saturday by an explosive device targeting his car in the town of Masyaf in Syria’s Hama province, according to the state-run Syrian Arab News Agency.

The center has long been linked by intelligence agencies to Syria’s chemical weapons program, and Israeli warplanes are suspected to have targeted the facility on at least two occasions over the past year, in September and July.

Syrian news reports blamed Israel’s Mossad intelligence agency for the killing and said Asbar had survived two previous assassination attempts, also by Israeli agents. According to the al-Watan Daily newspaper, he was killed because of his “important” work on Syrian defense systems.

“Yet again the Israeli enemy has assassinated one of the greatest Syrian minds,” al-Watan said in a commentary Tuesday.

Also Tuesday, the New York Times quoted an unnamed official with a Middle Eastern intelligence organization as confirming that Israel was responsible for the attack. The newspaper said Asbar had been collaborating with the commander of Iran’s elite Quds Force, Maj. Gen. Qasem Soleimani, on the production of precision-guided missiles in Syria.

An Israeli government spokesman declined to comment on the allegations.

If this new assassination was carried out by Mossad, it was the latest in a long line of Israeli attacks targeting Syrian weapons capabilities and development. Israel has carried out more than 100 airstrikes against targets in Syria since 2012, aimed either at Iranian military facilities or at attempts to transfer sophisticated weapons to the Iranian-backed Hezbollah militia in Lebanon.

The Syrian Scientific Studies and Research Center has long been a focus of international efforts to curtail Syria’s capacity to develop weapons of mass destruction, including chemical and biological weapons. A branch of the center outside Damascus was among the targets of U.S. strikes against Syria in April, and the U.S. Treasury Department has imposed sanctions on the institution since 2005.

After the Syrian government carried out what independent inspectors said was a sarin nerve agent attack that killed as many as 100 people in the town of Khan Sheikhoun in 2017, the United States also imposed sanctions on 271 individuals associated with the center.

Asbar was not among them, perhaps because he was associated with Syria’s missile program rather than the development of chemical weapons.

According to al-Watan, Syrian authorities had twice detained cells of local suspects allegedly recruited by Mossad who were engaged in monitoring Asbar’s movements. A faction of the main al-Qaeda affiliate in Syria called Abu Amara allegedly claimed responsibility for the assassination but was working on behalf of Israel, the newspaper said. There was no independent confirmation that an al-Qaeda affiliate was involved.

Syria’s missile development is a top concern for Israel, in part because of its worries over the expanding influence of Iran there.

The attack comes as Syrian troops regain territory along the 1974 line separating the Golan Heights from Syria. The countries have been in a state of war since 1948, when Israel occupied the Golan Heights. And though no shots have been fired since a 1974 cease-fire, Syrian President Bashar al-Assad continues to press for the return of the territory.

Syrian troops returned to the Golan Heights region last week after rebels who had controlled the area surrendered, restoring the status quo that had prevailed before the Syrian civil war. But their standoff has been further complicated by the extensive presence in Syria of Iran, which maintains advisers and allied militias embedded with the Syrian army.

Russia has been working to bring U.N. truce observers back into the area, but Israel continues to assert that it will take whatever action it sees fit to prevent Iran from establishing a permanent foothold in Syria, along its borders and elsewhere.

In an interview last week with Israel Radio, Israel’s minister for regional cooperation, Tzachi Hanegbi, cited Israel’s fears about the development of Iran’s missile capabilities in Syria as a top concern.

“What we have laid down as a red line is military intervention and entrenchment by Iran in Syria, and not necessarily on our border,” he said.

Correction: An earlier version of this story incorrectly reported how long Israel and Syria have been at war. It has been corrected.

Loveday Morris in Jerusalem contributed to this report.