PATNA: Bihar is tightening security ahead of Republic Day celebrations on Friday following threats by Maoist guerrillas.

The government has sounded an alert in the wake of intelligence reports that the outlawed Communist Party of India-Maoist could attack official celebrations.

"The police have alerted all police stations and heavy security arrangements are made for Republic Day," Bihar police chief AR Sinha said on Thursday.

In the past, Maoists have mainly targeted railways, government buildings and the police during Republic Days.