An alleged chemical attack in Syria last week did not involve use of a nerve agent but an extremely potent type of tear gas, British scientists analyzing video from the incident reportedly believe.

Scientists at the Porton Down military research institute say video of victims of the attack, which left 30 people dead and 80 injured in the northern Aleppo province last week, indicates they were exposed to a “super-strength tear gas,” according to the Sunday Times.

The British paper also reported Sunday that British spies had collected soil samples from the scene of the attack for further analysis.

According to the report, videos show victims suffering from respiratory failure, but not burns or further lung damage symptomatic of a nerve agent attack.

While Israel’s new intelligence minister, Yuval Steinitz, said chemical weapons were used, an unnamed US official told the Associated Press Thursday that Washington doubted the incident involved chemical weapons.

US officials won’t entirely rule out the possibility. But the source said additional intelligence-gathering led the US to believe more strongly that it was not a weaponized chemical attack.

The regime and rebels blamed each other for the attack.

The UN said on Friday it would launch a probe into the attack, after a request by Damascus.

Information provided by Syria, Britain and France on alleged chemical weapons attacks in Syria will be “crucial” in deciding the scope of the investigation the U.N. is planning, UN diplomats said.

Secretary-General Ban Ki-moon sent a letter to the UN Security Council on Friday indicating the possibility of a broader investigation, the diplomats said, speaking on condition of anonymity because the letter has not been made public.

There are fears embattled Syrian President Bashar Assad could use chemical weapons against his people in the ongoing civil war and also concerns that al-Qaeda linked rebels might obtain and use them.

The US has said the use of chemical weapons by Assad would cross a red line and draw international action, as would transferring them to Shi’ite terror group Hezbollah.

Israel’s National Security Adviser Yaakov Amidror said Saturday that concern over Syrian WMD, which he said could become a problem for Israel at any moment, was a key factor in Israel’s decision to issue a formal apology to Turkey over the killing of its citizens in the 2010 Mavi Marmara incident, so that Israel and Turkey could coordinate better over the dangers posed by Syria.