Russia said on Monday it was talking to the United States about the U.N. Security Council renewing an international inquiry into chemical weapons attacks in Syria, but Washington countered that Moscow had refused to engage on a U.S.-drafted resolution.

The mandate for the joint inquiry by the U.N. and the Organization for the Prohibition of Chemical Weapons (OPCW), which has found the Syrian government used the banned nerve agent sarin in an April 4 attack, expires on Friday.

Russia vetoed an initial U.S. bid to renew the joint investigation on Oct. 24, saying it wanted to wait for the release of the latest investigation’s report two days later. It has since proposed its own rival draft resolution.

“We are talking to the U.S., it’s not over yet,” Russian U.N. Ambassador Vassily Nebenzia told reporters on Monday.

The inquiry’s report found the Syrian government was responsible for the April 4 attack using sarin in the opposition-held town of Khan Sheikhoun, killing dozens of people. The Syrian government has denied using chemical weapons. Continue reading.