ISLAMABAD - Three labourers were killed and more than one dozen, including two Chinese engineers, got wounded when a blast occurred inside a tunnel at a construction site for a major dam project in Mujohi area near Muzaffarabad in the wee hours of Monday.

According to officials, the incident occurred due to a rock burst the in right tunnel of the Neelum Jhelum Hydropower Project, where two Tunnel Boring Machines (TBMs) were operational.

As a result, three local labourers died and 16 others including a Chinese engineer sustained injuries. The injured were immediately shifted to the CMH Muzaffarabad.

Till the filing of the report eight people were still admitted at the hospital and were out of danger, while seven others were discharged after first aid. The officials of Water and Power Authority insisted that there was neither any leakage of gas from the tunnel nor the tunnel collapsed and the accident was caused by the natural phenomenon of rock burst.

During excavation of tunnel natural stresses are created and when they break out, they release gases and rocks of different sizes, which damage manpower and machines deployed there. In order to avoid accident, holes are dug in periphery of tunnels to release pressure of rocks. On the advice of the international panel of experts, these holes were also made at Neelum Jhelum Project, the officials said.

The officials said that rock burst is a recurring phenomenon, which takes place during the process of tunnel excavation. However, in case of rock burst of higher magnitude, the damage is likely to be greater.

“We are working under 1.4 kilometer mountain, in coming days we would be working under 1.9 kilometers, until this phase is not completed there may be more cases of rock burst,” said a top official of the project.

This is not the first time that some accident has taken place at the project site. Last year, four people, including a Chinese engineer, had died when a wall collapsed at the construction site in December 2014.

“You have to understand it is an underground project; we are working under extremely tough conditions, that are the reason accidents happened despite our best efforts and cautions and safety measures,” the official said.

The 969MW Neelum-Jhelum Hydropower Project was scheduled to become operational by the end of 2016 but the deadline had been revised due to hostile contractors and financing challenges.

According to sources, PC-1 of the project has been sent for the approval earlier, this week.

After the approval, authorities would approach Chinese Exim bank as without PC-1 approval banks don’t offer loan to any project.

Last year, after the accident government had announced compensation for the deceased and wounded. This time no such announcement has been made so far.