Syria, which had claimed to have destroyed all of its chemical weapons production facilities, has revealed a previously undeclared research and development facility and a ricin-producing laboratory.

Reuters reports that, according to diplomatic sources, Syria detailed three new facilities to the Organization for the Prohibition of Chemical Weapons (OPCW) as part of an ongoing review of the government’s chemical arsenal.

The new disclosures lend support to accusations in recent months from some Western governments that Syria had not been upfront in its previous declarations regarding dismantling of its chemical weapons facilities.

The government of Syrian President Bashar al-Assad agreed last year to eliminate its entire chemical weapons program after a sarin attack on Aug. 21, 2013 killed hundreds of people in Ghouta, a neighborhood in Damascus. Syria has never declared it had any sarin, and blamed the attack on rebels.

Under the agreement between Damascus, Washington, and Moscow, reached under the threat of U.S. military action, the OPCW oversaw the destruction of 1,300 tons of chemical weapons that Syria declared to the Hague-based body.

Syria was supposed to have already destroyed all production, filling, and storage facilities. The new disclosures came as part of an ongoing review of “discrepancies” in Syria’s initial OPCW declaration, which Britain and the United States feared excluded some chemicals, notably sarin.

The chemical stockpiles Syria declared were all removed to a U.S. ship for destruction. A joint UN-OPCW team overseeing the process is due to return to the region this month for another round of discussions with Syrian officials.

Damascus revealed dozens of sites to the OPCW last year, but has now told a team of inspectors about three more facilities. One is a laboratory for the highly toxic ricin, at a site Syrian officials said was inaccessible due to ongoing fighting.

“Syria will argue that the facilities were not revealed earlier because they were in a rush when they first had to report them,” said one diplomatic source. “They had said the ricin was for medical purposes, but we don’t believe that’s true.”

Besides the highly toxic chemical stockpiles, an OPCW fact-finding team was assembled to look into dozens of reports of government chlorine “barrel bomb” attacks this year in Syria’s civil war.

Their report described eyewitness testimony of dozens of attacks in rebel-held villages and neighborhoods carried out with helicopters. The attacks killed several people and injured hundreds more.

Britain and the U.S. last week blamed the Assad regime for the chlorine attacks, noting that the government was the only party in the civil war with helicopters.