(Reuters) - A stream of volcanic lava menacing communities on the Big Island of Hawaii has stalled in its tracks after creeping toward populated areas for weeks but is expected to begin moving again fairly soon, scientists and local officials said on Wednesday.

The June 27th flow, named for the date it first bubbled out of the Kilauea Volcano, had been headed toward the town of Pahoa and was threatening to cut off a major highway and another road, officials said during a briefing with reporters.

But after about three months of steady movement, the leading edge of the flow came to a standstill on Sept. 22, though scientists and officials predicted it could resume its advance at any time.

"When the flow starts up again, and the question is when, not if, it will cross Highway 130," Hawaii County Mayor Billy Kenoi said.

Kenoi has said that some 8,000 people in the Puna district could be "lava-locked" if the flow blocked Highway 130, a route traveled by as many as 10,000 automobiles a day.

The U.S. Geological Survey said the flow had slowed to a fraction of the 260-meter daily advance it had been logging until last week, but fresh lava now oozing from through the Pu'u O'o vent on the eastern slope of the volcano could propel the stream forward again.

"It's plan for the worse, hope for the best," said Steve Brantley of the Geological Survey's Hawaii Volcano Observatory.

Scientists said they could no longer predict when lava might reach communities or whether it would continue its current track toward Pahoa, an historic former sugar plantation now home to roughly 1,000 residents.

"The flow is still active with small lava breakouts upslope from the lava flow's leading edge," Brantley said.

Crews were building temporary access roads and scrambling to protect Highway 130 to prevent it from being rendered inaccessible.

The Kilauea Volcano has continuously erupted from its Pu'u O'o vent since 1983. The last home destroyed by lava on the Big Island was at the Royal Gardens subdivision in Kalapana in 2012, according to Big Island Civil Defense.

(Reporting by Victoria Cavaliere in Seattle; Editing by Steve Gorman)