(Reuters) -- A spreading Alaskan wildfire has forced the evacuation of about 1,000 buildings but firefighters have gained ground by containing about 30 percent of the wind-driven blaze, a U.S. Forest Service spokesman said Monday.

The Funny River wildfire was burning on about 250 square miles (650 square km) of forest, most of it inside the Kenai National Wildlife Refuge in southern Alaska, said Willie Begay, the spokesman. The week-old fire has expanded from about 172 square miles (446 square km) on Sunday, when it was one-fifth contained.

The number of people affected by the evacuation of the buildings was not immediately known. Almost 600 firefighters are battling the blaze among rolling hills mostly covered with black spruce, Begay said. The area has been without rain for more than a month, and steady winds from the southwest are fueling the flames.

"Once it catches the wind in those areas, it's pretty fast-moving," Begay said. He added that rain might come in the next few days, which would help to put out the fire.

Warm and dry spring conditions have given the Alaska fire season an early start. The state Division of Forestry on Friday issued a statewide ban on outdoor burning.

(Reporting by Ian Simpson in Washington; Editing by Barbara Goldberg and Dan Grebler)

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