Nepalese security forces killed at least 32 Maoists and lost four of their personnel in fierce fighting on Tuesday.
Fighting erupted after the rebels attacked three police posts in Sirha district, the army said.
Hundreds of rebels attacked three police posts in Bandipur, Mirchaya and Daharapani areas in the district, 350 km south-east of Kathmandu, bordering India.
Nearly 26 Maoists were killed in Bandipur as the army repulsed the rebels who attacked the police post at 11.30 pm.
The five-hour gun battle ended on Tuesday morning, the army said. Four security personnel were also killed, it added.
Attacks were carried out at the Mirchaiya and Chauharwa police posts too.
While five rebels were shot dead in Mirchaiya, one was killed in Chauharwa, the army said.
The fresh violence coincided with the visit of the United States Assistant Secretary of State Christina Rocca, the first high-level visit after the February 1 power grab.