The 40-year-old Swedish lawyer accepted the 2017 Nobel Peace Prize on behalf of ICAN and its work championing an international treaty banning nuclear weapons.

Since Fihn took the reins of what was a small non-profit group in 2014, "the campaign has tripled in size and established itself as a powerful and modern global movement for nuclear disarmament," ICAN said.

It now consists of more than 650 partner organisations across 110 countries.

The organisation's crowning achievement was helping to convince 122 governments to negotiate and adopt the landmark Treaty on the Prohibition of Nuclear Weapons (TPNW) at the UN in 2017.

That treaty came into force last year and currently has 91 signatory states.

Fihn said she felt "enormously privileged" to have been executive director.

"With all the talent, commitment and strength in this movement right now, I am confident to hand over the leadership to someone new, and I know that ICAN will succeed and achieve its goal of prohibiting and eliminating nuclear weapons," she said.

Fihn did not divulge her plans but said she would remain engaged in the campaign and the work to ensure the implementation of the TPNW.

ICAN said its international steering group would recruit a new executive director "to build on Ms Fihn's achievements and drive ICAN's work towards the full implementation of the TPNW which has forged a strong international norm against nuclear weapons."

In the interim, current campaign coordinator Daniel Hogsta will become acting executive director from February 1, it said.