Police said they would be released later Thursday.
India has restricted fuel, medicine and other supplies for Nepal since the ethnic Madhesi group in the country`s south began protesting a new constitution adopted in September.
Members of the ethnic group say the constitution unfairly divides Nepal into seven states with borders that cut through their ancestral homeland. India has close cultural ties with the group and has asked Nepal to consider its demands for a bigger state, more seats in parliament and greater local authority.
Landlocked Nepal gets most of its fuel from India, as well as many other goods including medicine.
Protesters have blocked a key border point with India, and Nepalese officials say imports through other border points where there are no protests are difficult. India denies it has imposed a blockade.
At least 50 people have been killed in the protests since August.
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