(Recasts after evacuation order update)

July 10 (Reuters) - Oklahoma authorities on Sunday narrowed the scope of an evacuation order near the ONEOK natural gas plant following a fire on Saturday.

The Deer Creek Volunteer Fire Department told people on Saturday to avoid major U.S. Highway 81 in the area "due to a major fire at the ONEOK plant," posting an image of a large plume of dark smoke.

The evacuation decree, which previously covered areas two miles around the facility, has been set for a one-mile vicinity of the site, which is located near Medford, close to the border with Kansas, the City of Medford said on its Facebook page. Part of Highway 81 south remained closed, it added.

ONEOK did not immediately reply to an earlier emailed request for comment from Reuters on Sunday.

"We are cooperating with local emergency responders and appreciate their quick response," the company said a statement quoted by media on Saturday.

"Our focus continues working with emergency responders to extinguish the fire and the safety of the surrounding community and our employees." (Reporting by Costas Pitas in Los Angeles; Editing by Aurora Ellis)