A Swiss-born Islamic professor has become one of Europe's most talked-about Muslim leaders. Some praise him as a visionary religious scholar who teaches devout Muslims how to assimilate in a secular Europe. But others denounce him as an anti-Semitic firebrand, inspired by his fundamentalist heritage.

Tens of thousands of French viewers tuned in recently to an evening television program called 100 Minutes to Convince. It featured three of France's most controversial figures - Interior Minister Nicolas Sarkozy, far-right political leader Jean-Marie Le Pen, and Swiss Muslim scholar Tariq Ramadan.

And, as so often happens when Mr. Ramadan appears in public forums, ordinarily dull political banter turned into political fireworks - this time pitting Mr. Sarkozy against Mr. Ramadan.

France's Interior Minister challenged Mr. Ramadan to denounce the stoning of adulterous women, a practice condoned by some Islamic leaders, including his brother. Mr. Sarkozy also questioned Mr. Ramadan's support for French Muslim women who choose to wear veils. Mr. Sarkozy told Mr. Ramadan, "Tell French Muslims to make an effort to integrate. If you don't, it's because you are a master of double talk."

It's a label often put on the charismatic, controversial 41-year-old Swiss professor, whose biggest following is among the estimated 5-6 million Muslims living in France. Mr. Ramadan has been nicknamed the king of ambiguity, and the prince of double language.

Schooled in Swiss and Egyptian universities, Mr. Ramadan teaches philosophy in Switzerland, and lectures widely in Europe and the United States. He has authored several books about reconciling Islam and the West. The English edition of his latest work, Western Muslims and the Future of Islam, has just been published in the United States.

Mr. Ramadan says the book is as much a primer for non-Muslims, as it is a guide for Muslims living in the west. He wants to tell the west that Muslims can be as European as Christians and Jews. And he says that is a particularly important issue as Turkey encounters resistance to its effort to join the European Union.

"I think the great majority of Europeans think it is difficult, if not impossible, to be at the same time truly a European and truly a Muslim," he says. "Why all this discussion about Turkey [as a European Union candidate country]? Is it a Christian club? Or a club for all citizens promoting universal values and human rights?"

Critics argue Mr. Ramadan is far more conservative than he appears. They note that militant Sudanese Islamist leader, Hassan el Turabi, once called Mr. Ramadan the future of Islam.

Mr. Ramadan's grandfather was Hassan el Banna, who founded Egypt's banned Muslim Brotherhood movement. His father, who emigrated to Geneva and opened an Islamic center there, was considered the heir to Mr. el Banna's teachings. Last year, Mr. Ramadan's brother was suspended from his job as a Swiss teacher, for saying he favored stoning adulterous women to death.

Mr. Ramadan claims he has no ties with the Muslim Brotherhood, and has broken off contact with his brother because of the stoning remark. But that doesn't sway skeptics, like ethnic-Arab French politician Rachid Kaci, who calls the Swiss scholar an extremely dangerous man.

Mr. Kaci says Mr. Ramadan's claims to advocate a modern, moderate interpretation of Islam are only for Western consumption. The politician says when Mr. Ramadan speaks to young Muslims living in Europe his message is exactly the opposite.

Indeed, Mr. Ramadan's remarks offer support for critics and supporters alike. He blasts the French government for trying to cut French Muslims off from their religious heritage, for example, by barring girls from wearing headscarves at public schools. At the same time, he tells French Muslims to integrate into French society.

The Swiss professor sparked new controversy recently, by accusing several prominent French Jewish intellectuals of blindly supporting the policies of Israeli Prime Minister Ariel Sharon. Some pundits labeled him an anti-Semite, a charge he denies. "In every meeting, in every situation when we had this problem of anti-Semitic attacks, I was always saying no, it's not acceptable," says Mr. Ramadan. "I had Muslims saying Sharon is like Hitler. I was saying no you can't say that."

There is no doubt Mr. Ramadan's words are carefully listened to by many conservative Muslims in France, home to Europe's largest Islamic community. During a recent speaking engagement at a mosque near Paris, he was given a rousing welcome. He told the hundreds of young men, and headscarf-wearing women to be proud of their Muslim heritage, and to assert their rights. But he also said they must learn to live with secular European customs. His remarks were greeted with cheers.

The spokesman for the Union of Young Muslims of France, Abdelaziz Chambis, is among Mr. Ramadan's supporters. Mr. Chambis believes Mr. Ramadan is angering French leaders because he is saying that their integration schemes for Muslims are a failure. And Mr. Ramadan is telling them Islam, as France's second-largest religion, deserves its rightful place.

One of France's foremost experts on Islam, Franck Fregosi, says although not all Muslims agree with Tariq Ramadan, he has developed a large following through a combination of substance and style. Mr. Fregosi, notes that Mr. Ramadan is handsome and performs well on television. And unlike many Islamic preachers here, he speaks in French, rather than Arabic, which few second and third generation French Muslims understand.

Mr. Fregosi, an expert on Islam at France's National Center for Scientific Research, says Mr. Ramadan has influence because he captures the hearts and minds of young European Muslims like few other Islamic figures have. But Mr. Fregosi says it remains to be seen whether Tariq Ramadan's impact on Islam in Europe will ever match the intensity of the controversy he has sparked about himself.