Popes John Paul II and John XXIII will be declared saints on April 27 at a ceremony that might see two living popes honouring two dead ones. The Vatican has said retired Pope Benedict XVI might join Pope Francis in the saint-making ceremony.
"There's no reason – either doctrinal or institutional – that he couldn't participate in a public ceremony," the Vatican spokesman, Fr Federico Lombardi said.
He noted there was still time before the ceremony and that Benedict was free to decide what to do.
Benedict, who became the first pope in 600 years to retire when he stepped down in February, had said he would spend his final days "hidden from the world".
But he has taken on a more public profile recently, writing a letter to an Italian atheist that was published last week in Italy's 'La Repubblica' newspaper and appearing with Francis over the summer at a ceremony to unveil a Vatican statue.
Pope Francis had announced in July he would canonise two of the 20th Century's most influential popes together, approving a miracle attributed to John Paul and bending Vatican rules by deciding that John XXIII didn't need a second one to be canonised.
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Analysts have said the decision was aimed at unifying the church, since each pope has his admirers and critics.
Francis is clearly a fan of both: On the anniversary of John Paul's death this year, Francis prayed at the tombs of both men – an indication that he sees a great personal and spiritual continuity in them.
Originally, the canonisation was expected to have taken place on December 8.
But the first Sunday after Easter was chosen instead.