Two people were killed and two injured when attackers on a motorcycle threw two bombs into a mosque in a town in east Nepal, police said on Sunday.
Authorities imposed a curfew in parts of Biratnagar, 200 km (125 miles) southeast of Kathmandu, on the border with India, after the attack late on Saturday.
"Two bombs were hurled at the mosque. One went off and the other did not explode," police officer Yogendra Katuwal said.
"A small part of Biratnagar is under curfew," he added.
Majority-Hindu Nepal has no history of any serious conflict with Muslims who form a religious minority group.
A little known group called Nepal Defence Army in a statement to local media claimed the responsibility for the blast.
Madhav Raj Regmi, district administrator of Morang where Biratnagar is located said investigations were underway regarding the claim.
Biratnagar is the home town of Prime Minister Girija Prasad Koirala. (Reuters)
Two killed in Nepal bomb attack