More than twenty-thousand doctors have gone on strike in the north Indian state of Bihar to protest over new rules banning doctors at government hospitals from working in private practice.

A BBC correspondent in the Bihar capital Patna says medical services have been paralysed by the strike -- which is due to last for two days.

The Bihar government has invoked the Essential services Maintenance Act which makes the strike illegal, and drafted in back-up staff to provide an emergency service.

But our correspondent says big queues have already built up of people waiting for treatment.