Army officials in Nepal say they believe their troops have killed 500 Maoist rebels and wounded 200 others in a day-long firefight.
The army spokesman adds that 18 Nepali soldiers and policemen died in the fighting Sunday in the town of Beni, a district headquarters about 300 kilometers west of the capital.
If confirmed, it would be one of the bloodiest battles since rebels broke off talks with the government last August.
The army spokesman says fighting started late Saturday night with coordinated rebel attacks on facilities in Beni, including the town's jail, police and district administrative offices. Reporters near the scene say the rebels inflicted heavy damage.
The government says it flew reinforcements to the area by helicopter and fighting stretched into Sunday afternoon.
Officials say a separate rebel attack on an airport at Meghauli, south of Katmandu, interrupted operations but did not cause any casualties.
Maoist rebels have been fighting Nepal's constitutional monarch since 1996, and more than 8,500 people have died in the fighting.
Some information for this report provided by Reuters, AP and AFP.