Nigeria has arrested suspects after an Islamist militant attack on a Catholic church killed 40 people two months ago, chief of defence staff Gen Leo Irabor said on Tuesday.

Irabor said the attackers were arrested during joint operations involving the armed forces, the department of security services and police, privately owned Channels TV reported earlier.

It was not immediately clear how many suspects were taken into custody or where and when the arrests were made.

“It was my intention to present them to the public, but because of the investigation continuing I had to change my mind,” Irabor said.

“In due course the world will see them and others who are behind other daring attacks in the country.”

Nigerian authorities have said they suspect the insurgent group Islamic State West Africa Province carried out the massacre of members of a congregation inside the St Francis Catholic Church in the southwestern state of Ondo on June 5.