A Unicef official said that of the 49 polio cases, 16 are of the highly infectious polio strain virus P1 and the remaining are P3 strain cases.

'The detection of new P1 cases is a matter of serious concern,' he added.

Bihar recorded over 300 new polio cases in 2008, one of the highest since the polio immunisation drive was launched in the state nearly a decade ago, an official had said.

The state recorded 61 polio cases in 2006 and 193 cases in 2007.