Several thousand leftists shouting ``Nazi!'' and ``Fascist!'' gathered at Castel Sant'Angelo near the Vatican to protest Joerg Haider's visit, which has provoked an angry reaction as well from Jewish groups. In the past, Haider has praised some Nazi policies, though he later apologized for the comments.
John Paul held a private audience earlier with Haider and an Austrian bishop. Though the Vatican had hinted the pontiff might upbraid the politician for his hardline stances, John Paul voiced no criticism in brief public remarks, and Haider said he received a ``warm welcome'' from the pope.
The confrontations in the street came afterward, during a ceremony in St. Peter's Square to light the Christmas tree donated to the Vatican by the Austrian region of Carinthia, where Haider is governor - the reason for his visit to the Holy See.
Several hundred protesters, many garbed for battle in helmets, tried to force their way up the broad avenue leading to the square. They carried a big sign bearing a picture of the Nazi death camp Auschwitz and the words: ``Never again.''
Some demonstrators fired Roman candle firecrackers at police, others lobbed stones. Police responded with volleys of tear gas, keeping the crowd 500 yards from the piazza, where Haider was attending the tree lighting. The pope was not present. The demonstration broke up 30 minutes after the ceremony ended.
Haider ignored the protesters outside as he addressed the ceremony, speaking in Italian and dressed in traditional Austrian lederhosen. The light of the tree, he said, ``shines for all those excluded from the well-being of our civilization.''
A phalanx of police officers then escorted him to his nearby hotel. Helicopters buzzed overhead, part of the extremely tight security that surrounded Haider throughout his visit.
``If they want to save electricity, let them do it,'' Haider was quoted by the Italian news agency ANSA as saying.
``It is immeasurably sad that such a great pope would lower himself by meeting this international pariah,'' Lord Greville Janner, vice president of World Jewish Congress and a member of Britain's House of Lords, said in London.
``The response of Rome's Jewish shopkeepers is dignified and appropriate, and Haider's revolting response is precisely what you would expect of him. Even now, the pope should cancel the visit,'' he added.
Haider was joined by his wife and two children in his meeting with the pontiff, who met afterward with the entire 250-person delegation from Carinthia.
Asked if he and the pope spoke about immigration, Haider replied: ``No. We spoke about personal things. We spoke about issues which concern the world. I think the holy father wants to make clear that he is really happy to have us here.''
In brief remarks, John Paul spoke of the spiritual message of Christmas trees. His only reference to the controversy was to note that Carinthia announced the gift of the tree three years ago, before Haider became governor.
The pope gave Haider a copy of his World Day of Peace message, released Thursday, which among other topics mentioned the need for a ``cultural equilibrium'' combining openness to minorities with efforts to foster a common heritage.
The Vatican had earlier defended its decision to hold the audience with Haider, noting the pope traditionally receives similar groups in ``pastoral'' meetings.
``This gives Roman pontiffs full liberty to call the parties' attention to the respect for human and Christian values,'' it said, suggesting the pope might criticize Haider.
Since arriving in Italy on Friday, Haider has been highly visible, going shopping and holding several impromptu news conferences. He was to leave Saturday.
He angered the Italian government by accusing it of lax immigration policies, then scoffing at the president, who criticized his statement. In a newspaper interview he also suggested the Vatican shared his concern over Muslim immigration to predominantly Christian Europe.
The pope has consistently called for fair treatment of immigrants regardless of their religion.
Haider has been criticized for past remarks sympathetic toward aspects of Adolf Hitler's regime. Italy and the other European Union members imposed diplomatic sanctions on Austria in February when Haider's Freedom Party entered Austria's government, but lifted them in September.