"Send your third child to our organisation. It will help us in fighting suppression and will give you freedom from corrupt politicians and repressive security troops," read posters plastered in eastern Jharkhand state.
"We know of so many children working for the rebels. We can't do anything about it so it's better not to have a third child," said Dukha Manjhi, a local resident.
The separatists, who claim to be fighting for the rights of neglected tribes and poor farmers, already have a significant number of children in their ranks, often abducting them from their houses, police say.
The separatists justify child recruitment by saying they provide better opportunities to poor children who would otherwise work in factories and households.
Doctors said people were taking the order seriously.
"Earlier, people who were reluctant to use contraceptives are coming to us for information," said Manish Kumar, a doctor.

Copyright AFP (Agence France-Presse), 2006