United Nations inspectors have concluded there is "clear and convincing evidence" sarin gas was used in a large-scale chemical weapons attack in Syria on Aug. 21. 

“The environment, chemical and medical samples we have collected provide clear and convincing evidence that surface-to-surface rockets containing the nerve agent sarin were used ... in the Ghouta area of Damascus,” the U.N. says in a 41-page report.

U.N. inspectors were not tasked with determining who was responsible for the attack, which killed more than 1,400 people.

The White House on Monday said an initial review of the report bolstered the case that the regime of Syrian President Bashar Assad launched the chemical weapons attack. Press secretary Jay Carney said blood samples with sarin, as well as evidence that surface-to-surface missiles were used, backed up the findings of the U.S. intelligence community.

"The only group capable of delivering that attack both in the means that it was delivered, through surface to surface missiles, and the agent that was used, was the Assad regime," Carney said.

Secretary-General Ban Ki-Moon presented the report to the U.N. Security Council Monday morning, which he said describes inspectors’ interviews with more than 50 survivors, medical personnel and first responders.

“Over fifty interviews given by survivors and health care workers provided ample corroboration of the medical and scientific results,” the report says.

Victims of the attack experienced symptoms including “shortness of breath, disorientation, eye irritation, blurred vision, nausea, vomiting and general weakness.” Many of them, he said, eventually lost consciousness.

Thirty-four victims had their blood, urine, and hair samples drawn, which all showed signs of contamination, inspectors found.

Inspectors also determined the weather in Damascus that day maximized the impact of an attack involving heavy gases.

“The downward movement of air would have allowed the gas to easily penetrate the basements and lower levels of buildings and other structures where many people were seeking shelter,” the report says. 

The August attack, Ban said, was the most significant weapons attack against civilians since Saddam Hussein used them in Halabja in 1988.

“The United Nations Mission has now confirmed, unequivocally and objectively, that chemical weapons have been used in Syria. This is a war crime and a grave violation of the 1925 Protocol and other rules of customary international law,” he told Security Council members. “I trust all can join me in condemning this despicable crime.”

It’s now up to the Security Council to formally craft a resolution that would hold those who used the chemical weapons accountable through diplomatic means.

Secretary of State John KerryJohn Forbes KerryNorth Korea is moved by Pompeo diplomacy, but Dems dig in deeper Ex-Obama official Marie Harf, Guy Benson to co-host Fox News Radio show Five things to know about Russian oligarch Oleg Deripaska MORE and Russian Foreign Minister Sergey Lavrov agreed on a framework in Geneva Saturday that sets a tentative timeline for Syria to get rid of its chemical arsenal.

Within one week, Syria must submit a comprehensive list of its stockpile, and international inspectors would be required to be on the ground in Syria by November to inspect the weapons sites.

All of the chemical weapons must be eliminated by mid-2014, the plan says.

Ban said he endorses the plan, and hopes the Security Council moves “quickly to consider and implement” it. However, he also emphasized it could be difficult to enforce in the midst of a civil war.

More than 100,000 people have been killed since the war erupted in early 2011.  

Obama administration officials have reiterated that if Syria does not meet the resolution’s requirements, the U.S. may have to resort to military action.

President Obama, in his weekly radio and Internet address Saturday, said the U.S. would still maintain military pressure on Syria.

"Since this plan emerged only with a credible threat of U.S. military action, we will maintain our military posture in the region to keep the pressure on the Assad regime," Obama said.

"And if diplomacy fails, the United States and the international community must remain prepared to act."

— Justin Sink contributed.

This story was first posted at 9:56 a.m. and has been updated.