Christians who lay down their life to save others will now be eligible for beatification, the first step on the path towards sainthood, Pope Francis has said.

The Pope has opened up a fourth pathway to sainthood by decreeing that 'following in the footsteps and teaching of Jesus' in that way will become a new category for beatification alongside the three for which it has been reserved in the past: martyrs, those who have lived a life of heroic values and others with a clear saintly reputation.

'The heroic offering of life, suggested and sustained by charity, expresses a true, full and exemplary imitation of Christ,' Francis said in an apostolic letter.

Christians who tended to sick people with the plague and later died because of the disease could be included among candidates for the new pathway, according to the Vatican newspaper L'Osservatore Romano.

One candidate could be Chiara Corbella, a 28-year-old Italian woman who refused treatment for carcinoma, a type of skin cancer, while pregnant because it would have risked the life of her unborn child. She died nearly a year after giving birth, in 2012, when the cancer had become terminal and treatment was ineffective.

According to Pope Francis's letter, such Christians are 'worthy of that admiration which the community of the faithful has usually reserved for those who have voluntarily accepted the martyrdom of blood or have exercised the Christian virtues to a heroic degree'.

To be beatified, the 'free and voluntary offering of life' must be defined by 'the heroic acceptance out of charity of certain death in a short term', the letter said.

It added that possible candidates must have practised Christian values in their life before their selfless act and have a holy reputation, and must also be credited with a miracle after their death.

Christians who are sainted through martyrdom are the only ones who do not have to have been involved in a miracle.