Pope Francis, at the last minute, skipped reading his homily during a Palm Sunday Mass for tens of thousands of people at St. Peter's Square but continued presiding at the service.

In recent weeks the 87-year-old pope has been suffering on and off from bronchitis and influenza and has delegated an aide to read his addresses for him but on Sunday his prepared text was not read at all.

It is very unusual for a pope to totally skip a homily at a major event such as Palm Sunday.

The Vatican gave no immediate explanation for why the pope skipped the homily. The television coverage showed only the crowd for a few minutes instead of a close-up of the pope.

An announcer on Vatican Radio then said the pope had decided to not read the homily. The pope, dressed in red vestments, continued presiding, reading parts of the Mass.

Cardinals, priests, and bishops took part in the service that commemorates what the Bible says was Jesus' entry into Jerusalem days before he was betrayed, put on trial, and executed by crucifixion.

They, along with participants in the crowd, held palm fronds and olive branches at the service, which marks the start of Holy Week, a busy period leading to Easter.

Because of his knee ailment, for more than a year Francis has been presiding at Masses while sitting near the altar while a cardinals acts as the main celebrant.

After the Mass, Francis delivered his weekly Sunday Angelus message and blessing.