The curfew remained in effect in Surkhet from 11:00 am to 6:00 pm, according to officials.
The District Administration Office imposed the curfew with the possibility of demonstrations turning violent, Chief District Officer Baldev Gautam said.
The people in the district have been protesting for the past three days against the six-province model proposed by Nepal's four major political parties in the new constitution.
They have been demanding undivided Mid-West Region while delineating the federal provinces in the new constitution.
Markets, educational institutions, government offices and transport services have remained closed due to the agitation.
Three demonstrators were killed at Birendranagar yesterday after police opened fire at them.