UNITED NATIONS - Russia vetoed on Friday a Japanese-drafted U.N. Security Council resolution to extend by one month an international inquiry into who is to blame for chemical weapons attacks in Syria, just a day after Moscow blocked a U.S. push to renew the investigation.

The mandate for the joint inquiry by the U.N. and the Organization for the Prohibition of Chemical Weapons (OPCW), which was unanimously created by the 15-member Security Council in 2015, ends on Friday.

Syrian ally Russia has now cast 11 vetoes on possible Security Council action on Syria since the country's civil war began in 2011. The Japanese draft received 12 votes in favor, while China abstained and Bolivia joined Russia in voting no.

A resolution needs nine votes in favor and no vetoes by the United States, France, Russia, Britain or China to be adopted.

The inquiry, known as the Joint Investigative Mechanism (JIM), found the Syrian government used the banned nerve agent sarin in an April 4 attack and has several times used chlorine as a weapon. It blamed Islamic State for using mustard gas.

Russian U.N. Ambassador Vassily Nebenzia said the inquiry could only be extended if "fundamental flaws in its work" were fixed. He said investigators had for the past two years "rubber-stamped baseless accusations against Syria."

Russia vetoed on Thursday and on Oct. 24 U.S.-drafted resolutions to renew the inquiry. The council also voted on a rival Russian-drafted resolution on Thursday to renew the inquiry, but it failed after only garnering four votes in favor.

"Russia is wasting our time," U.S. Ambassador to the United Nations Nikki Haley told the council on Friday.

"Russia's actions today and in recent weeks have been designed to delay, to distract and ultimately to defeat the effort to secure accountability for chemical weapons attacks in Syria," Haley said.

After the meeting the council moved to closed-door discussions at the request of Sweden's U.N. Ambassador Olof Skoog to "ensure we are absolutely convinced we have exhausted every avenue, every effort" before the mandate expired.

While Russia agreed to the creation of the JIM, it has consistently questioned its findings and working methods.

The April 4 sarin attack on Khan Sheikhoun that killed dozens of people prompted the United States to launch missiles on a Syrian air base.

Syria agreed to destroy its chemical weapons in 2013 under a deal brokered by Russia and the United States.

(Reporting by Michelle Nichols; Editing by Phil Berlowitz and James Dalgleish) ((michelle.nichols@tr.com; +1 212 355 6053; Reuters Messaging: Twitter: @michellenichols))