New Delhi: The Centre on Monday asked nine states, including Naxal-hit Jharkhand and Chhattisgarh, to tighten their security and intensify vigil against possible strikes by Left-wing extremists on important installations.

The alert was sounded within hours of Maoists blowing up a railway track and bombing a mobile phone tower in Jharkhand during a 48-hour bandh called by them.

Apart from Jharkhand and Chhattisgarh, the communication was also sent to Orissa, Bihar, West Bengal, Andhra Pradesh, Maharashtra, Madhya Pradesh and Uttar Pradesh, home ministry official said.

The Maoists are observing a 48-hour shutdown beginning on Monday in the five states in protest against the alleged arrest of two senior members of the CPI (Maoist), a claim yet to be confirmed by the police.

There were intelligence inputs to suggest that Maoists may try to target some of the important places like railways, telecom, roads and power stations, the official said, adding the same had been shared with the state governments.

The blast left a big crater on the spot, about 200 km from Ranchi.