Finland's ex-president Martti Ahtisaari, who helped steer Namibia towards a peaceful independence, was awarded the Nobel Peace Prize Friday.

The Norwegian Nobel Committee gave the prize to Ahtisaari because of his "important efforts, on several continents and over more than three decades, to resolve international conflicts."

Ahtisaari, 71, joined Finland's Foreign Ministry in 1965 and spent two decades abroad -- serving as ambassador to Tanzania and then to the United Nations.

Between 1987 and 1991, Ahtisaari served as UN undersecretary of state for administration and management, heading a UN operation that aided Namibia's independence from South Africa in 1990.

From 1992 to 1993, Ahtisaari was chairman of the Bosnia-Herzegovina working group in the international peace conference on former Yugoslavia. He was also special adviser to the UN secretary-general on former Yugoslavia in 1993.

In August 2005, Ahtisaari helped negotiate an end to 30 years of fighting between Aceh rebels and the Indonesian government through his office, known as the Crisis Management Initiative.

Last year, his office also initiated secret meetings in Finland between Iraqi Sunni and Shiite groups to work out a peace deal.

Until March 2007, Ahtisaari, as a UN envoy, also led Serb-Albanian talks on Kosovo.

"For the past 20 years, he has figured prominently in endeavors to resolve several serious and long-lasting conflicts," the citation said, mentioning his work in conflicts from Namibia and Aceh to Kosovo and Iraq.

"He has also made constructive contributions to the resolution of conflicts in Northern Ireland, in Central Asia, and on the Horn of Africa."

Ahtisaari, who served as Finnish president from 1994 to 2000, said he was "pleased and grateful" for the award.

In an interview with NRK Norwegian TV Friday, Ahtisaari said he considered peace talks in Namibia as his greatest achievement.

"He has been one of the top trouble-shooters for the United Nations for more than a generation," Jan Egeland, a Norwegian former head of UN emergency relief operations, told Reuters.

Ahtisaari will receive the US$1.4 million prize in person this December in Oslo.

Former U.S. vice president Al Gore won the prize last year for his work on global warming.

With files from The Associated Press