Authorities in Nepal say one policeman has been killed and four wounded by a bomb that exploded as they were clearing a roadblock set by suspected Maoist rebels.

Authorities say the blast struck Monday on the Mahendranagar highway, about 600 kilometers west of the capital, Kathmandu.

The explosion comes on the second day of a week-long strike called by Maoist rebels to disrupt Wednesday's local elections to be held across the country.

The rebels have threatened to harm anyone who participates in the municipal elections. More than 600 candidates have already dropped out.

The rebels and opposition parties oppose the elections, calling them a sham aimed at legitimizing King Gyanendra's seizure of power a year ago in the constitutional monarchy.

The king says he took absolute rule because the government failed to stop the nearly decade-long Maoist insurgency.