The Russian government says there are “serious problems” with the international investigation into the possible use of chemical weapons in Syria in April.

Mikhail Ulyanov, the director of the Russian Foreign Ministry’s non-proliferation and arms control department, said Russia had to wait until the team released its next report to decide if it would support the extension of its mission.

The investigation was carried out by the UN and The Hague-based Organization for the Prohibition of Chemical Weapons (OPCW). It was created unanimously by the 15-member UN Security Council (UNSC) in 2015.

“In order to judge if it deserves an extension of the mandate, we need to see the report to be issued on October 26 and assess it,” Ulyanov said.

“I ask myself what is the reason for the extension of the mandate of this mechanism if it is not capable and is not willing to fulfill its mandate.” he said. “We will wait for the report and then we will define our position.”

The report said Syrian forces are responsible for three “chlorine gas attacks” in 2014 and 2015.

Meanwhile, Damascus turned over its entire chemical stockpile based on a deal reached by Russia and the U.S. back in 2013.