Construction workers found 34 bombs, probably of 1971 Liberation War period, while digging soil in Meherpur town on Wednesday.
Police recovered the bombs and claimed that 12 are still live.
According to police, one Hamidul Islam of Post Office area of Meherpur town bought a piece of land from one Lalu Mia several years ago.
On Wednesday, Hamidul engaged labourers to build a house there.
At one stage of digging, labourers found a few bomb-like objects eight feet under the soil.
Hamidul immediately informed the police. A team from Meherpur Sadar police station led by officer-in-charge (OC) Golam Rahman rushed to the spot and identified the things as bombs.
"We believe that the bombs recovered from under the soil are of Liberation War period and 12 of them are still live,” the OC said.
Police said Lalu Mia was a freedom fighter. He is now living in Dhaka.
"Police is trying to contact him", the OC said.