Nepal Prime Minister Sushil Koirala and other political leaders appealed for calm on Tuesdsay as anger flared over the killing of two demonstrators during a protest against the new constitution.
Hundreds of police reinforcements were sent to the country's troubled midwest, the day after the two protesters were killed when police fired in a bid to fend off an attack on the home of a local lawmaker.
Schools, shops and factories were also closed in Surkhet town as fresh demonstrations were staged against plans to divide the midwestern region into two provinces under a draft constitution that seeks to restructure Nepal as a federal state.
"Hundreds of security forces have been deployed in Surkhet and surrounding areas in case the situation turns hostile," said national police spokesman Kamal Singh Bam.
Koirala called for restraint saying negotiations over the new long-awaited constitution were ongoing.
"We appeal for the public to exercise restraint and help us with suggestions, stopping all protests," Koirala said in a joint statement with other political leaders.
"We will attempt to find solutions to the issues that have risen, keeping in mind the people's aspirations, and the country's need and interests," the statement added.
Bam said police had opened fire on Monday after the protests in Surkhet had turned violent.
"After crowds started attacking the house of a local MP and tried to vandalise offices yesterday, we were forced to use firepower and two protesters were killed in the firing," he told AFP.
Under the proposed constitution, which has been held up for years by political wrangling, Nepal will be divided into six provinces.
An agreement on the borders of the new provinces was struck at the weekend, after April's devastating earthquake helped bring a halt to the seemingly endless bickering between rival parties.
But the proposals have caused consternation in several parts of the country, including in the southern plains and the midwest.
"Our demand for an undivided midwest remains strong," said Tej Bikram Basnet, a teacher who joined the latest protest in Surkhet on Tuesday.
"We want to keep today's protest peaceful and don't want things to get out of hand like yesterday," Basnet added.
Surkhet, located 375 kilometres (230 miles) west of Kathmandu, is the capital of the midwestern region, which includes 15 districts.
Lawmakers began work on a new national constitution in 2008 following a decade-long Maoist insurgency that left an estimated 16,000 people dead and brought down the monarchy.
But parties were unable to reach agreement and the resulting uncertainty left Nepal -- one of the world's poorest countries -- in political limbo.