Russian President Vladimir Putin on Thursday told Prime Minister Benjamin Netanyahu that it was unacceptable to make "groundless" accusations over this week's suspected chemical weapons attack in a Syrian province.

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The Kremlin said in a statement that Putin "highlighted that it was unacceptable to make groundless accusations against anyone without conducting a detailed and unbiased investigation."

According to the Prime Minister's Office, it was Netanyahu who initiated the phone call in order to convey his condolences over the St. Petersburg attack. Netanyahu also told Putin that he was "deeply shaken by the chemical weapons attack in Idlib. The international community must complete the effort to clean Syria of chemical weapons as was agreed in 2013."

Scores were reported killed by a suspected Syrian government chemical attack in Idlib province and the U.S. government has suggested forces loyal to Syrian President Bashar Assad were responsible. Russia has said it was too early to accuse the Syrian government and called for an investigation.

The call came several hours after Defense Minister Avigdor Lieberman said that Assad ordered the chemical attack. Lieberman told Yedioth Ahronoth that Syrian planes carried out the two chemical attacks, which were “directly ordered and planned by Syrian President Bashar Assad.” He stressed he was “100 percent certain.” The defense minister said he did not know if Russia was involved in the attack.

Netanyahu, who severely condemned the usage of chemical weapons against innocent civilians in a statement on Tuesday, didn't point a finger at the Syrian president. "The horrible images in Syria should shock any human," Netanyahu said on Tuesday.

"Israel calls on the international community to complete its commitment from 2013 and remove the chemical weapons from Syria. The cruel war there highlights our great commandment – forever to protect ourselves against any enemy and against any threat."

After the attack, Israeli security sources told Haaretz that reports of the responsibility for the deadly chemical attack by the Assad regime are highly probable.

Sources in Israel said that the assault was approved by the highest levels of the Syrian regime, but at this point it is unclear whether Assad’s patrons, Russia and Iran, were involved.