Supporters of an ethnic minority group demanding changes in Nepal's new constitution have clashed with police and blocked main streets near the prime minister's office for a second straight day.

About 500 demonstrators gathered Monday, chanting anti-government slogans and attempting to push through a police barricade. Riot police using batons and demonstrators with sticks briefly clashed, but no serious injuries were reported on either side.

Security was stepped up around Singha Durbar, a fortified complex in Kathmandu that houses the prime minister's office and government offices, with hundreds of riot police guarding the streets.

The Madhesi minority group, which is leading the protest, wants a bigger state than assigned in the constitution adopted last year. Other minority groups that joined the protest want separate states for their populations as well.