VATICAN CITY: Pope Francis urged the United Nations on Tuesday to seek the "total elimination" of nuclear weapons, speaking as the United States and some other major powers boycotted a conference considering a global ban.

In a message to the conference that started in New York on Monday, Francis called on nations to "go beyond nuclear deterrence" and have the courage to overcome the "fear and isolationism" he said was prevalent in many countries today.

The United States, Britain, and France are among some 40 countries that have said they will not participate.

The United Nations General Assembly adopted a resolution in December - 113 in favour to 35 against, with 13 abstentions -that decided to "negotiate a legally binding instrument to prohibit nuclear weapons, leading towards their total elimination" and encouraged all member states to participate.

Francis said international peace and stability "cannot be based on a false sense of security, on the threat of mutual destruction or total annihilation, or on simply maintaining a balance of power".

"We need to go beyond nuclear deterrence: the international community is called upon to adopt forward-looking strategies to promote the goal of peace and stability and to avoid short-sighted approaches to the problems surrounding national and international security," he said.

US Ambassador Nikki Haley said it was not realistic to believe that countries such as North Korea would comply with any treaty.

Analysts say North Korea has likely mastered the technology to power the different stages of an intercontinental ballistic missile (ICBM) but is likely still a long way from being able to hit the mainland United States.

Francis, who has made several past appeals for a ban on nuclear weapons, urged countries to avoid the "mutual recrimination and polarization which hinder dialogue rather than encourage it".