The UK Ministry of Defense has claimed that chemical weapons were used in the Syrian conflict, the British Times reported Saturday.

Forensic evidence was collected after scientists analyzed soil smuggled out of the country in a secret British operation, the report said.

The sample was extracted from a neighborhood on the outskirts of Damascus in March by MI6 agents operating within Syria. The soil was then smuggled out of Syria and handed over to UK Ministry of Defense’s chemical and biological research department.

Military scientists said the soil contained traces of “some kind of chemical weapon,” though they could not positively identify the type of weaponized chemical.

“There have been some reports that it was just a strong riot-control agent but this is not the case – it’s something else, although it can’t definitively be said to be sarin nerve agent,” one source told the Times.

According to the newspaper, the British team was unable to say whether the chemical had been used by Syrian government forces or rebel fighters battling to topple the government of President Bashar Al-Assad.

They were further unable to determine to what extent chemical weapons had been used in the ongoing civil war.

The analysis provided the basis for diplomatic reports on Thursday that the West had “hard evidence” that chemical weapons had been deployed over the course of the two-year conflict.

“In one case, we have hard evidence,” one diplomat was quoted by AFP as saying, adding that “there are several examples where we are quite sure that shells with chemicals have been used in a very sporadic way.”

The British Ministry of Defense has yet to comment on the report, but the UK Foreign Office told AFP it was “deeply concerned” about the potential use of chemical weapons.

“We have shared our concerns with the UN secretary general and fully support his decision to investigate,” a spokesperson told the news agency.

The Syrian government as well as the rebels have accused one another of using chemical weapons in several recent incidents, particularly one in Aleppo in which nearly 30 people were killed.

The chairman of the U.S. House Intelligence Committee, Rep. Mike Rogers, later said that there is a “high probability” that Syria used chemical weapons in the ongoing civil war.

“We need that final verification, but given everything we know over the last year and a half, I would come to the conclusion that they are either positioned for use, and ready to do that, or in fact have been used,” he said.

Minister of Intelligence and Strategic Affairs Yuval Steinitz later said in an interview that it is “apparently clear” that either Syrian rebels or the Damascus regime have used chemical weapons in the country’s two-year civil war.

“This is very concerning for us and we must deal with it urgently,” said Steinitz.

The United Nations has said it will investigate whether chemical weapons have been used in the Syria conflict, but as of last week negotiators were stalled in talks over inspection of the sites where chemical weapons are stored in Syria.

A UN team is standing by in Cyprus, ready to be deployed within 24 hours, UN Secretary-General Ban Ki-moon said last week. The team would include at least 15 members, mostly from Nordic nations, Asia and/or Latin America and none a permanent member of the UN Security Council.