New Delhi, August 07: The Centre is trying to ascertain how the bridge over Irang river on National Highway 53, an alternate economic lifeline to Manipur, was cut off allegedly by activists of NSCN (I-M) despite a clearnace certificate given by army authorities that the road was �secured�.

The Army batallions, which acted as Road Opening Party, have been asked by the Defence Ministry to explain how the bridge was brought down at �their leisure using primitive measures including a saw to cut down the bridge�, informed sources said.

The Centre asked the army to �secure� the highway as this road is infested by insurgent groups of Northeast including NSCN (I M), NSCN(K) and UNLF after All Naga Students Association of Manipur (ANSAM) had blocked NH-39 to protest Manipur Government�s decision to declare June 18 as �Integrity Day�.

Manipur is connected to the rest of the country by NH-39, which passes through Nagaland and higher reaches of Manipur before entering Imphal valley.

The NH-53 connects Silchar in Assam to Imphal passing through Naga-dominated Tamenglong district in Manipur.

Besides the presence of insurgents, the condition of highway is bad in patches.

The local Army stations informed the higher-ups that the road had been cleared but the very next day, the bridge over Irang river was found collapsed.

On the preliminary investigation into the collapse, it was found that the bailey bridge over the Irang river had been cut off with bigger hexa blades-fitted saw, which takes a lot of time.

Due to plying of heavy vehicles, bridges on National Highway-53 at Makru and Barak were damaged but were repaired by Border Roads Organisation and opened for heavy vehicles from August two.

Further strengthening of bridges on National Highway-53 for sustained and regular movement of traffic is still continuing.

The State Government has reported that over 200 empty trucks have left Imphal on August two via National Highway-53 for Jiribam-Silchar.

Loaded vehicles with gross weight not more than 10 tons were plying on Jiribam and Imphal route.

This was effectively leaving a space of only three tons to be carried by a truck as the vehicle itself weighed seven tons.

Governments of Assam and Nagaland have been providing security to convoys of trucks in their respective territories.