Former pope Benedict said in a letter published in an Italian newspaper that he is in the last phase of life and on a "pilgrimage towards home".

Benedict, who in February 2013 became the first pope in six centuries to resign, wrote a letter to the Corriere della Sera newspaper thanking readers for their best wishes as he approaches the fifth anniversary of stepping down.

"I am moved that so many readers want to know how I spend my days in this, the last period of the life," he wrote.

"I can only say that with the slow withering of my physical forces, interiorly, I am on a pilgrimage towards home."

Since his resignation, the 90-year-old Benedict, a conservative German whose seven-year papacy was marked by mismanagement and financial scandals, has been living in a former convent in the Vatican gardens.

He has made only a handful of public appearances, mostly at major Church events but has received friends.

Those close to him say he is still sharp mentally but has mobility problems and needs a walker to get around.