Yenagoa - Pirates have killed two soldiers responding to a distress call in the restive oil-rich Niger Delta, a Nigerian military spokesperson said on Thursday.
The soldiers were killed on Wednesday in the creeks near Ijawkiri, an area in Bayelsa state, said military spokesperson Major Abubakar Abdullahi.
"Unfortunately, two gallant soldiers exhibited the highest point of patriotism by paying the supreme price while three others sustained gunshot injuries," Abdullahi said in a statement in Yenagoa, the state capital.
"Effort is ongoing by the Joint Task Force to track and apprehend the criminals," he said.
The Gulf of Guinea waters on the west African coast from Senegal to Cameroon are a piracy hotspot, with attacks ranging from armed robbery and kidnapping for ransom to hijacking of oil tankers.
In 2016, the region saw a "significant rise" in violence at sea, according to the Institute for Security Studies, a Pretoria-based research organisation.
The International Maritime Bureau recorded a "noticeable increase" of 36 attacks in Nigeria last year, up from 14 in 2015.
A combination of low global oil prices and a rise in militant attacks on pipelines tipped Nigeria into a recession in 2016.
Since President Muhammadu Buhari resumed amnesty payments to rebels in the region last year, attacks on oil infrastructure have waned in recent months, but piracy remains a growing threat.
Seven Russian sailors and one Ukrainian national were kidnapped from their cargo vessel off Nigeria's coast in February. They were rescued unhurt weeks later in March.