The Royal Nepalese Army says the high school students were taken by Maoist guerrillas last week from a remote mountainous village in Gumli district, about 300 kilometers west of Kathmandu.
They are the latest among thousands of students who are routinely picked up by the rebels for what are known as "indoctrination sessions." So far all abducted students have returned unharmed, usually in a day or two.
But worries have grown because the group abducted last Wednesday has still not reappeared. The army says it has mounted a search operation.
The head of Kathmandu's Center for Contemporary Studies, Lok Raj Baral, said taking away teachers and groups of students has become a common rebel practice. "The Maoists try to give lessons on their war, their mission, their objective etc., what they are doing for what reasons. It is a kind of indoctrination or familiarization. All the human-rights groups, they have been calling on the Maoists not to do such things, but they are following that practice," he said.
Last year a rebel leader objected to the word "abduction," saying the students are taken for "cultural campaigns."
The rebels have been waging a nearly decade-long campaign to turn Nepal into a communist republic, and have gradually consolidated their hold over large stretches of the countryside. The rebellion has claimed more than 10,000 lives.
Meanwhile, in Kathmandu, former Prime Minister Sher Bahadur Deuba and six former ministers have been cleared of corruption charges by a powerful anti-graft commission.
King Gyanendra fired Mr. Deuba's government in February, accusing him of failing to control the Maoist rebellion, and charging that politicians were corrupt.
Mr. Deuba and the ministers had been accused of distributing more than $50,000 of state funds to party workers. Although they were cleared of that charge, Mr. Deuba remains in detention on a second charge relating to the alleged embezzlement of funds for a road construction project.