The European Union formally opened membership talks with Turkey early Tuesday morning, but only after bitter opposition by Austria had exposed deep apprehensions about the future of the 25-country group and the prospects of admitting a large, poor, Muslim country to its ranks.

The last-minute discord forced postponement of the scheduled 5 p.m. Monday start of negotiations in Luxembourg. Turkish Foreign Minister Abdullah Gul refused to leave Ankara, Turkey's capital, for the talks until E.U. members reached a final consensus to work toward full membership for his country.

"We have reached a historic point," Gul said in Ankara after receiving word of that accord. He boarded a plane for Luxembourg, and an official opening ceremony took place shortly after midnight.

The accord moves Turkey an important step closer to its four-decade-old goal of joining the community of European nations. It is widely predicted that the membership talks, in which the bloc will set benchmarks for Turkey to meet in areas such as human rights and economic and democratic reform, will last 10 to 15 years. At the end, there is no guarantee that Turkey will be admitted.

The E.U. countries unanimously agreed last year to open talks with Turkey on Oct. 3. But in recent days, Austrian officials reversed themselves and said Turkey should be offered a "privileged partnership" rather than full membership.

Because E.U. rules allow countries to veto new members, Austria's opposition threatened to block the talks from beginning. The uncertainty during two days of emergency talks over the weekend deepened the sense of crisis that has plagued the European Union since voters in France and the Netherlands rejected its proposed constitution during the summer.

Austria's last-minute resistance infuriated some members of the union, particularly Britain, which saw it as a betrayal of long-standing promises to Turkey.

Many analysts interpreted the defeats of the constitution as strong signals that Europeans believe the organization is bureaucratic, unresponsive and undemocratic. Many people who voted "no" cited concerns about bringing Turkey in.

"There is the question if the E.U. can take this, if we are paying enough attention to our people," Austrian Foreign Minister Ursula Plassnik told reporters in Luxembourg before relenting, according to the Reuters news agency. "Austria is listening to the people."

Opposition has stirred emotions in Turkey as well. Prime Minister Recep Tayyip Erdogan told lawmakers in his party on Sunday that Turkey was part of "a project for the alliance of civilizations," according to the Associated Press. He said he hoped the European Union would "show political maturity and become a global power." If it did not, he said, it would "end up a Christian club."

Austria has historic animosities with Turkey dating to the expansion of the Ottoman Empire into Europe, and today, Austrians rank among the most opposed to Turkey's membership. Some European diplomats suggested that the Austrian government's action was tied to regional elections Sunday in the province of Styria, in which Chancellor Wolfgang Schuessel's Austrian People's Party lost its 60-year grip on power there.

Austrian officials demanded that if Turkey was going to start talks, Austria's close neighbor Croatia should also be allowed to do so.

Croatia's membership bid was frozen by the European Union in March because of U.N. complaints that the country was not cooperating in bringing an indicted war crimes suspect to justice. But on Monday, the U.N war crimes prosecutor, Carla Del Ponte, told reporters in Luxembourg that "for a few weeks now, Croatia has been cooperating fully with us." And late Monday night, E.U. ministers also announced they would begin membership talks with Croatia, giving Austria a diplomatic victory.

Turkey has territory in geographic Europe -- the historic center of its largest city, Istanbul, is located on the European side of the Bosporus Strait. But many Europeans contend that culturally and religiously, the country is simply not part of Europe.

"The E.U. is a historical union, not just a financial one, and their history is more linked with the Near East and Middle East," said Caroline Vidal, 26, a Paris midwife.

In a July survey by the German Marshall Fund, only 22 percent of people polled in nine of the European Union's biggest countries said Turkish membership would be "a good thing," while 29 percent said it would be "a bad thing" and 42 percent said it would be "neither good nor bad."

The opening of talks with Turkey also coincides with anxiety in Europe about the rise of radical Islam, terrorist bombings in Madrid and London, increasing immigration and sluggish European economies. Turkey has 70 million people, 99 percent of whom are Muslim, and a per-capita GDP of $6,772, leading many Europeans to argue that the would-be member -- which has more people than any E.U. country except Germany -- is too big, too poor and too Muslim to join their union.

Turkey could siphon billions in agricultural and infrastructure subsidies from other nations or send waves of impoverished Turks to their countries, some Europeans fear. Turkey shares 1,040 miles of border with Iran, Iraq and Syria, and its membership would bring Islamic fundamentalism to Europe's doorstep, these critics argue.

A key stumbling block for Turkey has been its refusal to recognize Cyprus, now an E.U. member, which Turkey invaded in 1974 after an attempted coup by Greek Cypriots. Turkey continues to control the northern part of the island. Some Europeans also criticize Turkey's checkered human rights record, particularly its treatment of ethnic Kurds.

Supporters of Turkey argue that it has been a member of NATO since 1952, that it is a member of the Organization for Cooperation and Security in Europe and that it was a bulwark against communism during the Cold War. Now, they say, Turkey can be an important bridge between Islam and the West.

The country adheres to a strict separation of mosque and state. Many European political leaders call Turkey the model of a modern, democratic Muslim country that Europe should embrace as an example to the world. And while poor, they say, its large population offers a rich opportunity for investment and trade.

In a speech last month, British Foreign Secretary Jack Straw said Turkish membership would "demonstrate that Western and Islamic cultures can thrive together as partners in the modern world."

Turkey's Prime Minister Recep Tayyip Erdogan smiles after E.U. ministers agreed to launch membership talks delayed by internal discord.Austrian Foreign Minister Ursula Plassnik objected late in process.