A nun who was battling Katy Perry over the sale of a convent in Los Angeles reportedly collapsed and died during courthouse proceedings for the case.

Eighty-nine-year-old Sister Catherine Rose Holzman was part of a small group of (naturally) prudish nuns from the Sisters of the Immaculate Heart of Mary who had objected to Perry's attempt to buy their old convent.

The nuns have said they are not happy with the content of Perry’s music videos, and that they don't want their successor on the property to be a girl who kisses girls.

They say selling the property to Perry would mean “being forced to violate our canonical vows to the Catholic church”.

Entering the courthouse before her death, she had addressed Perry via broadcaster KTTV, saying: “To Katy Perry, please stop. It’s not doing anyone any good except hurting a lot of people.”

Perry originally offered to buy the eight-acre (three-hectare) property for $14.5m to use as a private residence in 2014.

When the nuns researched Perry and found out more about her “public image” they objected to selling her the property “for what should be obvious reasons coming from Catholic nuns,” attorneys wrote.

The accepted a competing $15.5m bid from a hotelier, but the dispute has dragged on as the archdiocese sued to block the sale in 2015.