The United States said on Friday it could not rule out Russian help to separatists in Ukraine in firing an SA-11 surface-to-air missile that likely downed a Malaysian airliner in eastern Ukraine with 298 people on board.

U.S. Ambassador to the United Nations Samantha Power told the U.N. Security Council that a Malaysian Airlines Boeing 777 was "likely downed by a surface-to-air missile... operated from a separatist-held location in eastern Ukraine."

"Because of the technical complexity of the SA-11 it is unlikely that the separatists could effectively operate the system without assistance from knowledgeable personnel, thus we cannot rule out technical assistance from Russian personnel in operating the system," Power said.

Russia’s U.N. envoys says pressure should not be brought on investigation into downed Malaysian airliner with statements trying to prejudge outcome.

Russia's U.N. Ambassador, Vitaly Churkin, took part in and addressed the council.

While Ukraine had SA-11 systems in its inventory, Washington was not aware of any of those systems being in the area where the plane was downed on Thursday, Power said. She added that Ukrainian military had not fired any missiles during the crisis.

The U.N. Security Council on Friday called for a "full, thorough and independent international investigation" into the downing of the Malaysian airliner, urging all parties to grant investigators access to the site.

In a statement agreed by consensus, the council also called for "appropriate accountability." Britain drafted the short text and hoped the 15-member council could issue it on Thursday, but Russia requested more time to review it before it was agreed.

U.N. political affairs chief Jeffrey Feltman told the Security Council that he would travel to Moscow and Kiev in the coming days. He also said the U.N. International Civil Aviation Organization (ICAO) made an offer to Ukraine to put together an international team of investigators.