Pope John Paul II has a high fever but is responding when addressed by aides, the Vatican has said in a statement.
The Pope asked not to return to hospital for treatment
At an earlier briefing the Vatican spokesman said the pontiff had begun to drift in and out of consciousness.
Cardinals who have seen the 84-year-old Church leader, who is suffering from heart and kidney problems, say he is propped up in bed and seems at peace.
Thousands of people have gathered in St Peter's Square and many have been chanting the Pope's name.
The latest Vatican medical bulletin, issued at 1720 GMT on Saturday, said the pontiff's condition remains "very serious" and he had developed the high fever in late morning.
"When addressed by members of his household, he responds correctly," the statement said.
Earlier, Spokesman Joaquin Navarro-Valls stressed the gravity of the Pope's condition.
"Since dawn this morning there have been first signs that consciousness is being affected," he said.
'About to die'
Newspapers in Italy and across the world splashed farewell messages to the Pope on Saturday.
Prayers have been offered up for the pontiff worldwide
"Long Farewell to the Dying Pope" read a headline in La Repubblica while Il Tempo simply said "Ciao, Karol", using the Polish-born Pope's original first name.
All Italian sports competitions were suspended on Saturday out of respect for the pontiff, the Italian Olympic Committee said.
The head of the Vatican's health care office told Mexican TV the Pope was "about to die".
"I talked to the doctors and they told me there is no more hope," said Mexican Cardinal Javier Lozano Barragan.
Correspondents in Rome say the mood is one of sadness and resignation, as the city prepares to say goodbye.
A nun in the city said that while she felt sadness at the Pope's approaching death there was " happiness that his suffering will end because he's truly suffering".
Heading for Rome
Having refused to return to the Gemelli hospital where he was treated last month for breathing difficulties, the Pope is being treated in his Vatican apartment by a team of four top consultants and his private doctor, Renato Buzzonetti.
His condition had deteriorated on Thursday after he developed a urinary tract infection that later brought on "septic shock and a cardio-circulatory collapse", and he received the last rites.
Cardinals in the US and Latin America have indicated they are preparing to travel to Rome.
John Paul II's eventual successor will be elected in a secret vote at the Vatican's famed Sistine Chapel by the cardinals - the "princes" of the Christian world's largest Church.
Prayers for the Pope have also been offered by other religions: Jews in Jerusalem and Muslims in Indonesia.
The Communist authorities in Cuba allowed the Church leader there, Cardinal Jaime Ortega, to make a rare statement on television.
Many view the undermining of Communism in Roman Catholic countries of Eastern Europe as one of the Polish pontiff's main achievements.