Security has been increased at the Hindustan Aeronautics Limited unit at Ojhar, about 21 km from Nashik, Maharashtra, after the state-owned enterprise received an anonymous letter threatening to blow up the premier aerospace company's production unit, a top police official said today.

The four-line letter, written in Hindi and received by the Ojhar-based unit on Saturday, warned that 'Bambai-Malegaon ab Ojhar MIG... bas thoda intezar' (after Mumbai and Malegaon now Ojhar-MIG... in a little time), Superintendent of Police (Nasik range),

Rajvardhan, told PTI this morning.

Security has been enhanced at the Ojhar airport and a strict bandobast was being maintained at the 42-year-old company's factory and the HAL employees' residential colony.

Following the police official's meeting with the HAL top brass, close circuit cameras were also installed at the unit's main gate.