Meta's Oversight Board on Wednesday overturned a decision to remove a video that was shared on Instagram showing the gruesome aftermath of an attack on a church in Nigeria that killed at least 40 people.

The video showing motionless, bloodied bodies on the floor, apparently the aftermath of the church attack that took place on 5th June in Owo, southwest Nigeria, was shared by an Instagram user on the same day.

Meta removed the video, saying hashtags added by the user could be read as glorifying violence and minimizing suffering. The user appealed against the removal to the independent board.

The board on Wednesday asked Meta to restore the post with a "disturbing content" warning screen, saying this would protect victims' privacy while allowing for discussion of events.

"Nigeria is experiencing an ongoing series of terrorist attacks and the Nigerian government has suppressed coverage of some of them, though it does not appear to have done so in relation to the June 5 attack," the board said.

"The Board agrees that in such contexts freedom of expression is particularly important."

Nigerian authorities have accused insurgents from the Islamic State in West Africa group of carrying out the attack on St Francis Catholic Church, which took place during Pentecost Sunday mass. Five suspects were arrested in August.

The Nigerian government has been exploring ways to regulate social media use in the country, Africa's most populous. Millions of Nigerians are active users of YouTube, Twitter, Facebook and TikTok.

The West African country has asked Google to block the use of YouTube channels and livestreams by banned groups and terrorist organizations in the country.