The spokesman for the U.S.-led coalition fighting Islamic State militants says contacts with Russia are underway to avoid friction on the ground between U.S.-allied fighters and Syrian troops backed by Moscow around Syria's largest oil field, coveted by both sides.

Col. Ryan Dillon told The Associated Press on Monday that the coalition will continue to "de-conflict" with the Russians, to ensure allied forces and the coalition air support can operate safely in and around the Al-Omar oil field.

The U.S.-backed Syrian Democratic Forces captured Al-Omar on Sunday, narrowly beating the Russia-backed Syrian troops who were also advancing toward it.

Dillon says SDF fighters are fighting remaining IS militants in a housing complex adjacent to the oil field. He says the SDF will continue to secure key areas and will attack further into IS-held areas along the border with Iraq and in the oil-rich region of Deir el-Zour.