More than 8,700 people died in two major quakes that hit Nepal on April 25 and May 12, destroying nearly half a million houses and leaving thousands camping out in the open.
"Cases of abuse and violence have been reported in the camps, and some women complain of feeling insecure living there," said police official, Tara Devi Thapa, who is coordinating the classes.
"These skills will help them feel confident against attackers and will be useful for their protection," Thapa told AFP.
"Don't think you are weak just because you are a woman," said constable Pramila Khadka.
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"Listen to me attentively, and you won't have trouble tackling even someone stronger than you," Khadka, a judo player, told the women.
Taking turns at playing attackers, the participants partnered with each other and practised kicks, punches and locking moves designed to disarm opponents, as police shooed away curious male onlookers.
"Living here is not like home, you are surrounded by strangers all the time. But now if a boy tries to tease me, he won't be safe," Rai told AFP.
Police official Thapa said more than 40 women and 80 children have attended the classes so far and plans were under way to extend the training to other camps as well.
Widespread unemployment, poverty and the impact of a 10-year Maoist insurgency have made Nepali women and children easy targets for traffickers, and campaigners say that the recent disaster has increased the threat.