Israel has a presence in Syria and it is thus logical that it would know if chemical weapons had been used in the civil war, a Syrian rebel leader has claimed.

Speaking to CNN, the Chief of Staff for the Free Syrian Army, General Salim Idriss, said Israel is one of the countries that now has “many, many” security services inside Syria.

He told the news network he believes Israel’s Mossad is in the country.

Idriss was responding to remarks by the head of the Research Section of Military Intelligence in the IDF, Brig. Gen. Itay Brun.

Brun said at a conference held by the Institute for National Security Studies on Tuesday that Bashar Assad’s regime had used chemical weapons in Syria recently.

Several people were killed as a result of this, he said.

“To the best of our professional understanding, the regime has made use of deadly chemical weapons against the rebels in a number of incidents in the past few months,” he said, referring to a March 19 incident in Aleppo province in which 31 people were killed, apparently by chemical agents.

Evidence could been seen in the physical symptoms suffered by those who had apparently been exposed to chemical agents, he said.

The White House later said that the United States has not yet concluded that Assad’s regime used chemical weapons against rebel forces, but backs a probe into the matter. U.S. Defense Secretary Chuck Hagel urged caution Wednesday over the Israeli claim, saying all evidence must be weighed carefully as such allegations are “serious business”.

Idriss told CNN, however, that he can confirm that the Syrian regime has used chemical weapons in the Syrian cities of Homs, Aleppo and Otaiba, outside Damascus.

“We took some samples of the soil and of blood. The injured people were observed by doctors and the samples were tested and it was very clear that the regime used chemical weapons,” he said.

Idriss said his doctors gave the samples to “observers” of the civil war in Syria, but refused to name which groups.

Both Britain and France now say soil samples indicate “some use of chemical weapons.”

The general also denied Syrian government accusations that the opposition groups have used chemical weapons.

“That is just a kind of propaganda,” he said. “I can tell you that we don’t have chemical weapons. We [wouldn’t] like to have such kind of weapons.”

Syria’s Information Minister claimed on Wednesday that Damascus will not use chemical weapons against its own citizens, or in the event of war with its neighbor Israel.

Minister Omran al-Zoubi said Syria would not resort to chemical weapons even if it had to go to war with Israel and use “all resources.”

“Even if Syria does have chemical weapons, our leadership and our military will not use them either against Syrians or against Israelis, above all for moral reasons and secondarily on legal and political grounds,” Zoubi reportedly said at a Moscow university.