Bishops in Brazil, the country with the largest Catholic population in the world, led special services for the pontiff. Latin America is home to nearly half of the world's 1.1 billion Roman Catholics.
Communist Cuba's state-run media allowed Havana's Catholic cardinal to make a rare television appearance to tell the island's people, who have little access to unrestricted news, about John Paul's decline.
Church leaders in the Philippines, with the biggest Catholic population in Asia, have been leading fervent prayer vigils.
Words of concern for the pope have also come from such countries as Australia, India and Russia, as well as most of Europe -- especially in John Paul's native Poland, where churches remained open throughout the night.
In the Middle East, Muslims joined Christians in expressing concern for the pope, who was known for his support of inter-faith dialogue.
In Washington, the White House said President Bush and his wife, who are not Catholic but are devout Christians, are praying for the pope. If John Paul dies, news reports here quote senior officials as saying Mr. Bush will travel to Rome to attend funeral ceremonies.
Information for this report is provided by AP, AFP and Reuters.
