After initial examinations, police said the weapons might have been left there by Pakistani Army during the Liberation War of 1971.

Some labourers while digging earth inside Shibganj Police Station for foundation of a building at around 10:30am came across 23 hand grenades stored in a clay pot.

As they dug further, they found three more grenades, a rocket launcher, a pipe bomb, and a blank magazine of a light machine gun (LMG) at around eight feet below the ground.

The pipe bomb is nearly one foot long and has a fin attached to its back and a fuse on its head. "It (the bomb) is usually used during wars," said Sub Inspector Mahfuz, who had received training in firearms from Bangladesh Army.

Deputy commissioner and superintendent of police of Chapainawabganj yesterday visited the scene.

"We have kept the munitions in a safe place inside the police station. We are not yet sure whether they are live or not. We are waiting for army experts to examine those," said Superintendent of Police Moinul Islam.

He said that the weapons are rusted, making the inscriptions illegible.

"Pakistani forces might have dumped those in 1971 when they used the police station as a military camp," he added.

"We stopped the construction work after the incident. We will request the army experts to determine whether there is a possibility of finding more firearms and ammunition buried underground," the SP said replying to a question.