Parishioners have voiced objections to the use of cement and sand in restoring the 176-year-old St Mary’s Basilica.
Heritage experts warn that cement is incompatible with the original lime and granite construction of the site.
The 1840-built church is an internationally recognized site elevated to basilica status by the Vatican in 2008.
Church authorities have promised to reconsider their renovation methods following the criticism from heritage conservationists.