By Charles Haviland
BBC News, Kathmandu
Two people have been killed and at least one more injured after a mosque was bombed in Nepal's second biggest city, Biratnagar.
Reports say two men on a motorcycle hurled four bombs at the Choti mosque during evening prayers on Saturday.
Three of the devices exploded, and two of the people who were seriously injured died on their way to hospital.
A shadowy Hindu extremist group - the Nepal Defence Army - said in a statement it carried out the attack.
The group first emerged more than a year ago, saying it was fighting to preserve Nepal's old status as a Hindu state.
An indefinite curfew has been imposed in the district.
Most of Nepal's small Muslim minority live in the southern plains, where Biratnagar is situated.
For many months the region has seen ethnic tensions, with numerous antagonistic factions emerging.
Violence grounded in religion is rare, but some Hindu nationalists have threatened that it will increase because, they say, there is widespread resentment over Nepal being declared a secular state.
Nepal's monarchy is closely bound-up with Hinduism. But after King Gyanendra's royal government fell in 2006 the restored parliament declared the country secular.
Political violence has been steadily rising in the run-up to elections due in less than two weeks.