The 120-member assembly brings together deputies from the ethnic Albanian population, a majority in Kosovo, and lawmakers from other ethnic groups, including 22 Serb lawmakers.
"This is a historical day for Kosovo," Hans Haekkerup, the top U.N. administrator of the province, told the legislators, who were searched before entering the building and had to walk through a metal detector to reach the chamber.
Referring to former Yugoslavia's communist past, he said, "For the first time in history, we are now participating in the opening of a truly democratically elected assembly representing the people of Kosovo."
Nexhat Daci, a member of the moderate Democratic League of Kosovo, was selected as speaker of the parliament.
The legislature will be the third force to govern the province alongside U.N. officials and NATO-led peacekeepers, who took control of Kosovo in June 1999 after 78 days of NATO airstrikes.
The alliance launched the air war to force former Yugoslav President Slobodan Milosevic to end his crackdown on ethnic Albanians.
The U.N. administrator reserves the right to veto any decision, and the assembly is not allowed to take up such contentious issues as the final status of Kosovo.
All ethnic Albanian parties want Kosovo to become independent, but the Serbs insist it remain part of Yugoslavia.
Haekkerup told deputies they have to assume "a very demanding task, taking decisions that will influence the life of each and every citizen in Kosovo." That will require "a high degree of wisdom and moderation."
"You will also bear the responsibility for ensuring that interethnic and political reconciliation takes firm root in Kosovo and that all communities enjoy equal rights and responsibilities free from any form of discrimination," he added.
Haeekerup also read a message from U.N. Secretary General Kofi Annan: "This is a day of hope but also an occasion for reflection and renewed resolve. You face the challenge of achieving efficient daily government in particularly difficult circumstances.
"At the same time, you have an important task in overcoming the legacy of the past and establishing a political culture of tolerance, mutual respect and constructive compromise," the message said.
The assembly was scheduled to reconvene on Thursday to elect the president of Kosovo. Ibrahim Rugova, whose Democratic League of Kosovo won the Nov. 17 elections, was seen as a favorite.
But his party's margin is not large enough to govern without forming a coalition. A minimum of 61 votes are needed to elect the president.
International officials organized elaborate security arrangements.
The Serb members had to be escorted to the building and will be taken back to their homes by a total force of 200 international police officers. Some 100 lcal police officers working under the supervision of United Nations police have been trained to secure the area around and inside the building.
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