"The process is irreversible," the former Finnish president and career diplomat, who was deeply involved in the negotiations on Kosovo's status, told reporters in Oslo as he prepared to receive his Nobel prize.

"Kosovo is independent, it will remain independent. It has been recognised by over 50 countries, but more important, countries which represent, I think, 65 to 70 percent of the world economy," he said, adding that he expected more nations to join the list.

Ahtisaari, who has spent 30 years helping end conflicts in troublespots around the world, played a key role in bringing an end to hostilities in the breakaway Serbian province of Kosovo in 1999.

At the end of 2005, he was appointed the United Nations special envoy for talks on Kosovo, but failed to clinch an agreement between Belgrade and Pristina.

Kosovo, with a 90-percent ethnic Albanian population, unilaterally declared its independence on February 17 this year to the great dismay of Serbia and Russia, but Washington and most European Union countries quickly recognised it as a sovereign state.

"I hope that we can get Kosovo into international financial institutions as fast as possible," Ahtisaari said.

As for the Serbs, the Finn said that before they could enter the EU, "they have to be able to live with their past and recognise themselves that something went terribly wrong, among other things, in their relationship with Kosovo."

Nobel laureate lauds EU mission to Kosovo

His comments came as the EU's justice mission for Kosovo, EULEX -- the bloc's biggest ever civilian operation -- officially took over Tuesday from a post-war UN mission that has been in the disputed territory since 1999.

Initially comprising 1,900 staff, EULEX faces a difficult task to win over a hardcore of sceptical ethnic Albanians and Serbs while overseeing Kosovo's transition to statehood.

"I'm very pleased that the EULEX has started," Ahtisaari said, adding however that Russian opposition to Kosovo's independence was not likely to weaken any time soon.

"I don't see any great changes in the Russian attitude," he said.

Ahtisaari, who has figured among the frontrunners for the Nobel Peace Prize for years, won this year's award "for his important efforts, on several continents and over more than three decades, to resolve international conflicts," including in the Balkans, Indonesia and Namibia.

Ahtisaari was the best choice for the Nobel Peace Prize according to Kosovo's Prime Minister Hashim Thaci.

"The Nobel Peace Prize accorded to President Ahtisaari is a prize given to the right person, to the man ... who contributed so much for global peace and especially for the cause of Kosovo," Thaci told The DPA news agency in Pristina. Kosovo declared independence on guidelines laid by Ahtisaari.

Ahtisaari urges parties to work towards Middle East peace

Ahtisaari took the opportunity of his Nobel Prize ceremony to urge "all the parties involved" to work for a solution to the Middle East conflict.

"The credibility of the whole international community is at stake," Ahtisaari said in his acceptance speech. "We simply cannot go on, year after year, simply pretending to do something to help the situation in the Middle East."

He urged US president-elect Barack Obama to give "high priority" to the conflict and called for continued commitment from the other members of the Quartet on the Middle East, a group including the United Nations, the United States, the European Union and Russia.

"Peace is a question of will. All conflicts can be settled, and there are no excuses for allowing them to become eternal," he said.

Outgoing Norwegian Nobel Committee Chairman Ole Danbolt Mjos lauded Ahtisaari for "important efforts, on several continents and over more than three decades, to resolve international conflicts."

Peace negotiator joins exclusive list

Ahtisaari, 71, joined an "exclusive group of peace negotiators," Mjos said mentioning former US President Theodore Roosevelt (1906), former UN Secretary General Kofi Annan (2001) and former US President Jimmy Carter in 2002.

Mjos noted that Ahtisaari personally rated his efforts in Namibia the highest, noting he had been called "Namibia's midwife" for his role in negotiating Namibia's independence from apartheid South Africa.

In his remarks, Ahtisaari said "the mediator's role combines those of a ship's pilot, consulting medical doctor, midwife and teacher."

He reminded guests at the ceremony including Norwegian King Harald V of his personal experience as a displaced person. As a child he was one of hundreds of thousands forced to relocate from Karelia that Finland had to secede to the Soviet Union during World War II.

Ahtisaari urged governments to stick to their goals of "eradicating poverty" despite the financial crisis and said future peace processes will need broader participation, including women.

Other guests included Queen Sonja, Ahtisaari's wife Eeva and son Marko, Finnish Prime Minister Matti Vanhanen, Finnish Foreign Minister Alexander Stubb and Norwegian cabinet members including Prime Minister Jens Stoltenberg.

The Peace Prize is one of the awards endowed by Swedish industrialist Alfred Nobel. In accordance with Nobel's will, the peace prize is handed out in Oslo.

The Nobel prizes for medicine, physics, chemistry, literature and economics were to be handed out later Wednesday in the Swedish capital, Stockholm.