Hundreds of minority ethnic group supporters have scuffled with police in Nepal, restarting protests against the government and the Himalayan nation's new constitution.

The supporters on Sunday blocked a main street leading to the prime minister's office in Kathmandu, creating traffic problems. They attempted to break through a police cordon, but were quickly pushed back.

No one was injured. Security was stepped up, with hundreds of riot police guarding the streets.

The protesters, led by the Madhesi minority group, are demanding changes in the new constitution adopted last year. Their protests from September to February resulted in the deaths of more than 50 people and severe shortages of fuel and other supplies.

They have vowed to continue protesting in Kathmandu until their demands are met.