The ailing Pope will be 82 on Saturday
John Paul II does not rule out resigning as Pope if his health deteriorates further, a Honduran cardinal has told reporters in Rome.
Italian TV says Archbishop Oscar Maradiaga's announcement is likely to fuel the debate about the ability of the ailing Pontiff to continue in his position.
The Vatican has declined to comment, and BBC correspondent David Willey in Rome says the cardinal was speaking off the cuff.
"The Pope is fully aware of his responsibility and when he realises that he can no longer go on, he will have the courage to say: I quit," Archbishop Maradiaga was quoted as saying by AFP news agency.
Globe-trotting invalid
Pope John Paul will be 82 on Saturday. He suffers from Parkinson's disease - an incurable degenerative disorder - and is crippled by knee and hip problems.
Next week he is due to depart for Azerbaijan and Bulgaria as part of his efforts to improve relations with Muslims and Orthodox Christians.
Further onerous travel plans this year include returns to Canada, Latin America and Poland.
At a general audience in St Peter's Square on Wednesday, the Pope appeared to rule out any immediate intention on his part to lay down his high office.
"I count on your spiritual support to continue faithfully in the ministry that the Lord entrusted to me," he said, responding to birthday greetings from the crowd.
Correspondents say the Vatican is sensitive about allowing the Pope to appear in a wheelchair and has been improvising with a mobile platform during public ceremonies.
Resignation questions
Under the Roman Catholic Church's canon law, it is technically possible for a pope to resign, but no pope has ever left office voluntarily in modern times. In the event of a papal resignation, a conclave of cardinals would have to be summoned immediately to elect a successor.
Pressure for the Pope to resign has come from liberal Catholics hoping that a successor might relax Church views on contraception, abortion, women's ordination and celibacy.
Some conservatives are also reported to favour a papal resignation, apparently because they are angry over series of millennium initiatives including apologising for the sins of Catholics through the centuries.
At the beginning of 2000, the head of Germany's Roman Catholic bishops raised the possibility that the Pope might step down because of ill health, but this was dismissed as it would have meant him not leading jubilee celebrations which he considered an important milestone.
The is no provision in Church law for forcing a pope to resign or the removal of an incapacitated pope.