Pope Francis has denounced what he called the “hidden euthanasia” of old people at a special event at the Vatican.

The elderly were well represented among tens of thousands of people at Sunday’s open-air mass.

Former Pope Benedict, now 87 and making only his third public appearance since his resignation, was warmly embraced by his successor.

Francis said having the Emeritus Pope living in the Vatican was “like having a wise grandfather at home”.

An affectionate tribute, but his message to the throng was deadly serious.

The Pope denounced what he called a “throwaway culture” where old people were discarded – and said old people’s homes could not become “prisons” where business interests took precedence over care.

“A society which doesn’t care for its grandparents has no future,” he said. “People have no memories and sever their roots.”

The crowd were treated to a performance by Italian tenor Andrea Bocelli singing “Con te partirò” – known in English as “Time To Say Goodbye” but which literally means “With You I Will Leave”.

According to the World Health Organisation, the number of people over 60 is expected to double over the next decade – and more than treble by 2050 to two billion, most in the developing world.