President Barack Obama on Monday offered appreciation and prayers on behalf of all Americans to Pope Benedict XVI, following the pontiff's shock announcement that he would resign.

"The Church plays a critical role in the United States and the world, and I wish the best to those who will soon gather to choose His Holiness Pope Benedict XVI's successor," Obama said in a written statement.

"Michelle and I wish to extend our appreciation and prayers to His Holiness Pope Benedict XVI," Obama said, saying he and his wife warmly remembered meeting the pope in 2009.

The pope announced on Monday he will resign because of old age, becoming the first pontiff in more than six centuries to step down in a move that stunned the world.