In stepped up violence in Nepal, security forces killed 16 Maoists in an exchange of fire in the country's west where the rebels attacked a security checkpost and triggered an explosion in a market Monday, killing three soldiers and a civilian.

Security sources said the rebels attacked a security checkpoint at Kavrebhanjyang along Banepa-Bardibas highway in Kabhrepalanchwok district in which three soldiers were killed.

The security forces on the scene retaliated and the two sides exchanged fire for an hour. A civilian was also killed in the crossfire.

In a separate incident, the rebels triggered an explosion in a busy market at Chipledhunga area in Pokhara, 200 km west of Kathmandu, in which 12 people were injured.

The explosion was targeted at security personnel, but it missed the target injuring pedestrians and shopkeepers.

Suspected Maoists also shot dead a taxi driver in Dulegauda area of Tanhu district for defying their general strike in the area.

As part of their offensive against rebels, security forces Sunday launched an operation to flush out the rebels in Baldhengadi and Satyabati areas of Palpa district, the army said.