A group of protesters attacked the police officers with petrol bombs, stones and bottles, and attempted to storm a police station in the southern town of Gaur, Nepal officials said on Sunday.

"The police fired in self-defense after the protesters became aggressive, and unfortunately one (protester) was killed," district chief Narahari Baral told the AFP news agency.

The alleged rioter was 18-years-old, according to the police. Over a dozen members of Nepal's security forces were reportedly injured in the clashes.

Authorities have imposed an indefinite curfew in the area.

Death toll mounting

The riot on Sunday is only the latest in a series of protests organized by Nepal's minorities over the new constitution.

The document, which was adopted in September, divides the Himalayan country into seven states or provinces.

Madhesis object to dividing their ancestral homeland into two regions, saying that they would be dominated by other ethnicities. Other minorities also claim that the new charter leaves them with too little representation within the government.

The ethnic group has close cultural and linguistic ties with India, and Kathmandu has accused India of backing their protests.

At least 50 have been killed in clashes over the constitution since the violence first erupted in the summer of 2015.

The government and ethnic groups have pledged to continue negotiating, despite slow progress.

dj/xx (AP, Reuters, AFP, dpa)