The United Nations said it discovered five bombs in a wall of Mosul’s iconic al-Nuri mosque, planted years ago by ISIS, during restoration work in the northern Iraqi city.

Five “large-scale explosive devices, designed to trigger a massive destruction of the site,” were found in the southern wall of the prayer hall on Tuesday by the UNESCO team working at the site, a representative for the agency told AFP late Friday.

Mosul’s al-Nuri mosque and the adjacent leaning minaret nicknamed al-Hadba or the “hunchback,” which dates from the 12th century, were destroyed during the battle to retake the city from ISIS.

Iraq’s army accused ISIS, which occupied the city for three years, of planting explosives at the site and blowing it up.