The Siddhartha Highway is some 300 km west of Kathmandu, Palpa district police said in a press statement.
Hundreds of passengers were left stranded after the guerrillas took away the keys of the vehicles that were plying on the road, the statement noted, adding, "The Butwal-Tansen road section of the highway, which links Butwal city of Rupandehi district with Tansen city of Palpa district of western Nepal, has been hardest hit."
Vehicles plying from western hilly areas including Tansen and Pokhara cities, and Syangja, Gulmi and Arghakhanchi districts were stuck in the middle of the road, the statement added.
The statement quoted security forces in the area as saying that the road will be opened soon.
Meanwhile, people in the Eastern Nepal have been isolated due to the guerrillas imposed road blockade since last two weeks, according to the statement.
People in Taplejung, Paanchthar and Ilam districts, some 500 km east of Kathmandu, have been isolated and are facing shortages of daily groceries as no vehicles plied on the road, the statement said.
The guerrillas had torched some half-a-dozen of passenger buses in eastern part of Nepal, saying that operators defied the strike, which was called by the guerrillas along the Mechi Highway since mid-July, the statement added.