The 82-year-old head of the Roman Catholic church who appeared unhurt, was quickly helped to his feet and resumed the mass at St Peter's Basilica on Thursday, making no reference to the incident as the service started.

Etchegaray, 87, suffered a broken femur bone and was taken to hospital, Lombardi said.

The woman, whom Lombardi described as "unstable", was detained for questioning by Vatican security police.

She was the same person who tried to jump a barricade to get close to the pope at last year's Christmas Mass, the spokesman said.

In his message to more than 10,000 people during the Christmas Eve mass - held two hours earlier than the traditional midnight hour this year to ease the pope's busy holiday schedule - the pontiff urged the faithful to put aside the complexities and burdens of daily life and rediscover the simplicity of the Christmas message.

"We live our lives by philosophies, amid worldly affairs and occupations that totally absorb us and are a great distance from the manger," he said.

"In all kinds of ways, God has to prod us and reach out to us again and again, so that we can manage to escape from the muddle of our thoughts and activities and discover the way that leads to him," he said.