OSLO (REUTERS, AFP) - The Norwegian Nobel Committee, warning of a rising risk of nuclear war, awarded the 2017 Nobel Peace Prize on Friday (Oct 6) to a little-known international campaign group advocating for a ban on nuclear weapons.

ICAN describes itself as a coalition of grassroots non-government groups in more than 100 nations. It began in Australia and was officially launched in Vienna in 2007.

More than 70 years since atomic bombs were used on the Japanese cities of Hiroshima and Nagasaki, the Nobel committee sought to highlight ICAN's tireless non-proliferation efforts.

ICAN's Executive Director Beatrice Fihn told Reuters the group was elated. Asked if she had a message for North Korea's Kim Jong Un, who has tested nuclear arms in defiance of global pressure, and US President Donald Trump, who has threatened to "totally destroy" North Korea to protect the US and its allies, she said both leaders need to know that the weapons are illegal.

"Nuclear weapons are illegal. Threatening to use nuclear weapons is illegal. Having nuclear weapons, possessing nuclear weapons, developing nuclear weapons, is illegal, and they need to stop."

"We live in a world where the risk of nuclear weapons being used is greater than it has been for a long time," said Berit Reiss-Andersen, the leader of the Norwegian Nobel Committee.

In July, 122 nations adopted a United Nations Treaty on the Prohibition of Nuclear Weapons, but nuclear-armed states including the United States, Russia, China, Britain and France stayed out of the talks.

"This award shines a needed light on the path the ban treaty provides towards a world free of nuclear weapons. Before it is too late, we must take that path," ICAN said in a statement on its Facebook page.

"This is a time of great global tension, when fiery rhetoric could all too easily lead us, inexorably, to unspeakable horror. The spectre of nuclear conflict looms large once more. If ever there were a moment for nations to declare their unequivocal opposition to nuclear weapons, that moment is now."

ICAN also blasted some nations for clinging to their weapons in the name of security. "The belief of some governments that nuclear weapons are a legitimate and essential source of security is not only misguided, but also dangerous, for it incites proliferation and undermines disarmament," ICAN said.

In its citation, the Nobel committee noted that ICAN has been the "leading civil society actor in the endeavour to achieve a prohibition of nuclear weapons under international law".

"The Committee wishes to emphasise that the next steps towards attaining a world free of nuclear weapons must involve the nuclear-armed states. This year's Peace Prize is therefore also a call upon these states to initiate serious negotiations with a view to the gradual, balanced and carefully monitored elimination of the almost 15,000 nuclear weapons in the world," it added.

ICAN's spokesman said on Friday the organisation was overjoyed at that it had won the prize. "As you can imagine we are elated, this is great news," Daniela Varano told Reuters. "It's great recognition for the work that the campaigners did throughout the years and especially the Hibakusha," she said, referring to survivors of atom bombs in Japan.

ICAN has mobilised campaigners and celebrities alike in its cause. Its high-profile supporters include former UN Secretary-General Ban Ki Moon, Nobel laureate Desmond Tutu and singer and artist Yoko Ono.

The Nobel prize seeks to bolster the case for disarmament amid nuclear tensions between the United States and North Korea and uncertainty over the fate of a 2015 deal between Iran and major powers to limit Teheran's nuclear programme.

The Iran deal is seen as under threat after Trump called it the "worst deal ever negotiated". A senior administration official said on Thursday that Trump is expected to announce soon that he will decertify the pact, a step towards potentially unwinding it.

The committee raised eyebrows with its decision to award the prize to an international campaign group with a relatively low profile, rather than giving it to the architects of the Iran deal, who had been widely seen as favourites after hammering out a complex agreement over years of high-stakes diplomacy.

"Norwegian Nobel Committee has its own ways, but the nuclear agreement with Iran achieved something real and would have deserved a prize," tweeted Carl Bildt, a former Swedish prime minister who has held top posts as an international diplomat.

The leader of the Norwegian Nobel committee denied that the prize was "a kick in the leg" for Trump and said the prize was a call to states that have nuclear weapons to fulfil earlier pledges to work towards disarmament.

"The message is to remind them to the commitment they have already made that they have to work for a nuclear free world," Reiss-Andersen told Reuters.

The UN said the award would help bolster efforts to get the 55 ratifications by countries for the UN Treaty on the Prohibition of Nuclear Weapons to come into force. "I hope this prize will be conducive for the entry into force of this treaty," UN Chief Spokeswoman Alessandra Vellucci told a news briefing.

Nato member Norway congratulated ICAN but said it would not sign the treaty to ban nuclear weapons. The Nobel Peace Prize is awarded by a committee appointed by the Norwegian parliament. "Norway will not support proposals in the UN that would weaken Nato's role as a defence alliance," Prime Minister Erna Solberg said.

More than 300 people and organisations were thought to have been nominated for this year's Peace Prize, including the UN's refugee agency UNHCR, Syria's White Helmets rescue service and Congolese doctor Denis Mukwege.

The prestigious award is given to a person, or group of people, who have done the most or the best work for fraternity between nations.

Last year's prize was awarded to Colombian President Juan Manuel Santos for his efforts to end a 52-year-old war with Marxist rebels, a surprise choice after Colombians voted against the accord in a referendum. Other past recipients include Martin Luther King Jr., Nelson Mandela, Mother Teresa, Aung San Suu Kyi and Malala Yousafzai .

The Peace Prize, which comes with a golden medal and a cheque for nine million Swedish kronor (S$1.5 million) will be presented in Oslo on Dec 10, the anniversary of the death of its founder, Swedish businessman and philanthropist Alfred Nobel.