A churchgoer in her 80s had the best intentions when she attempted to restore a 19th-century fresco of Jesus at a church in Spain.

But her botched efforts have infuriated officials from The Sanctuary of Mercy Church in Zaragoza and has left them scrambling to determine if the 120-year-old artwork can be saved.

The elderly woman acted without authorization from anyone, according to the Centre for Borjanos, which had already received a donation from the granddaughter of the artist Elias Garcia Martinez to professionally restore it.

Excess moisture in the church over the last 18 months had caused the Ecce Homo to deteriorate.

The centre said no one realized what the senior was doing until she had finished.

The value of the small mural was not very high, the statement said, but it holds a sentimental value. The church is considering legal action against the woman, according to a blog for the centre.

Spanish newspaper Heraldo de Aragon reports the original painter's family believes the damage done to the artwork is "irreversible." Professional restorers will assess the wrecked painting.

The woman responsible, identified in Spanish media as Cecilia Gimenez, told TV station RTVE that the priest was aware of her intentions.