ISTANBUL — Turkey’s constitutional court disbanded the only pro-Kurdish party in Parliament on Friday, a move that could threaten efforts to resolve the conflict with the Kurdish minority by peaceful means.

The court in Ankara ruled that the Democratic Society Party was undermining national unity and cooperating with the PKK, the Kurdish rebel group that has been fighting for autonomy in southeastern Turkey since the early 1980s.

The court ejected two party leaders from Parliament, including the party’s chairman, Ahmet Turk, and barred them and 35 other party members from politics for five years.

“No political party has the right to make use of acts and rhetoric of violence,” the chairman of the court, Hasim Kilic, said Friday in a televised press conference. “It has to make a distinction between peaceful language, suggestions and acts of violence.”

Mr. Kilic did not cite the specific allegations that led to the verdict, which is expected to be published in full next week. But he said the party had become “a focal point of the activities against the country’s integrity” and that it had ties to a “terrorist organization.”

Responding to the decision, Mr. Turk, the party chairman, said that while he still held out hope for a peaceful and democratic resolution of the Kurdish conflict, the ban would be counterproductive.

“Turkey is going through a painful period, and of course blocking democratic politics deepens the sense of hopelessness,” he told reporters outside party headquarters in Ankara. “Turkey cannot resolve this conflict by party closures but only through the use of reason, logic and dialogue.”

The decision appeared to be a setback for the government’s efforts to bring Kurds into the political system. Last month, the government presented a landmark plan calling for the free use of the Kurdish language in the media and in political campaigns, restoring Kurdish names to towns that had been given Turkish ones, and a new committee to fight discrimination.

The Kurdish party, known as the DTP, applauded those efforts but has refused to join the government and other lawmakers in calling for the Kurdish rebels to lay down their arms, a position many analysts believe led to the court’s ruling on Friday.

The DTP has also refused to denounce the PKK as a terrorist organization, as it has been classified by Turkey, the United States and the European Union.

Such positions show that the DTP “has not absorbed the constitutional principles well and cannot refrain from supporting anti-democratic tendencies,” Emre Kongar, a professor of political science, said on NTV, a private television station. But others said the ruling would do little to end the violence that has taken more than 40,000 lives in the last three decades.

“In today’s environment armed conflict still continues,” said Sezgin Tanrikulu, the former head of the bar association in Diyarbakir, largest Kurdish city in Turkey. “The exclusion of legitimate actors from political grounds will destroy the already weak belief among Kurds that the conflict can be resolved through political means.”

The court’s decision could also damage Turkey’s prospects for joining the European union, which has warned Turkey against banning political parties.

While the government, led by the Justice and Development Party, has tried to work with the Kurds, who make up nearly 15 percent of the population, the more conservative state establishment, which includes the judiciary, has generally considered their political movement a threat to national unity.

The government’s efforts have also been complicated by a recent surge of unrest in the Kurdish regions, which has fed the anger of nationalists.

Widespread Kurdish street protests broke out two weeks ago when rumors circulated on the Internet that the imprisoned PKK leader, Abdullah Ocalan, had been mistreated. Since then, the Interior Ministry says, 799 people have been detained, 119 arrested and hundreds have been injured in clashes between the police and Kurdish demonstrators.

The Justice Department said the rumors were false and published photos of Mr. Ocalan’s cell, hoping to stem the unrest.

But the violence escalated Monday when a Kurdish student was killed by the police in Diyarbakir and seven Turkish soldiers were killed in an ambush near Tokat, in the north-central part of the country.

A radical wing of the PKK claimed responsibility for the attack.

The DTP denounced it.