The Nigerian army has arrested three militants suspected of having been involved in the killing of four soldiers and seized a large weapons cache, it said on Tuesday.

Two weeks ago the army said gunmen dressed as priests killed four soldiers in the oil-producing Niger Delta region which has been rocked by violence and militant attacks on oil pipelines.

The army said that in a shootout on Monday it killed several militants belonging to the Niger Delta Avengers group, which is accused of being involved in the killing of the soldiers, and arrested three other suspects.

Large quantities of arms, ammunition and a gunboat had been seized, it said in a statement.

The Niger Delta Avengers group has claimed responsibility for a string of attacks on oil facilities to press for a greater share of oil revenues and development for the poor region. It did not claim the attack on the soldiers.

On Sunday a statement attributed to the Avengers said the group was ready for a ceasefire and a dialogue with authorities. Government officials have refused to comment on the ceasefire offer.

Pipeline attacks have reduced the OPEC member's output by 700,000 barrels a day to 1.56 million bpd.

•Text courtesy of Reuters.