Dhaka: Two border guards from Bangladesh have been shot dead by Indian troops near a frontier post, triggering an immediate protest by Dhaka, a Bangladeshi security official said on Friday.

"Indian Border Security Forces [BSF] suddenly started firing when our forces were patrolling along the northwestern frontier on Thursday night," said Major Mahmud, of the Bangladesh Rifles border guards.

"Two of our soldiers had been fatally hit. It's [a] serious violation by the BSF. We have lodged a strong protest with the BSF over the incident," he said.

India's BSF said it was chasing cattle smugglers when Bangladeshi border guards fired at guards, forcing them to retaliate.

"One of our guards was hit in the firing and we think the Bangladesh Rifles had no business to be on our side of the border," Ashish Kumar Mitra, the BSF chief, said.

Prior exchanges

Despite generally friendly relations between the two countries, Indian and Bangladeshi border guards often exchange fire along their 4,000-km porous border, which runs through rice fields, hills, jungles, marshes and rivers.

They accuse each other of frequently targeting civilians on the frontier, known for rampant smuggling and illegal migration. Both sides accuse each other of helping smugglers as well.

In 2006, at least sixteen Indian and three Bangladeshi soldiers were killed in the deadliest border clash between the two countries.