The recommendation was one of 60 put forward by the 14-member Weapons of Mass Destruction Commission to help the world free itself of nuclear, biological and chemical weapons.
Blix, who led the UN search for mass destruction weapons in Iraq launched months before the US-led 2003 invasion, turned the report over to UN Secretary-General Kofi Annan three years after the commission was set up at the initiative of the Swedish government.
Blix's inspectors found no mass destruction weapons while in Iraq but had to cut short their mission when the war began. U.S. experts later also failed to find any banned arms.
The independent commission, in its 231-page report, also called for negotiations to continue to convince Iran to suspend sensitive enrichment-related programs, as called for by the UN nuclear watchdog agency in Vienna as well as by the UN Security Council.
Iran, the world's fourth-largest oil exporter, says it wants only to produce electricity but major Western powers accuse it of using a civilian nuclear program as a cover for the production of atomic weapons.
Israel is widely assumed to already have nuclear weapons but has never acknowledged them and – unlike Iran – is not a member of the nuclear Non-Proliferation Treaty (NPT).
Legally binding commitment
On other global challenges, the commission called for the pursuit of a verifiable international agreement holding North Korea to a 1992 commitment to keep the Korean peninsula free of nuclear arms, nuclear reprocessing and uranium enrichment.
It said major powers acknowledging nuclear arsenals should provide legally binding assurances to those countries without atomic arms that they will not come under nuclear attack.
It called on all nuclear powers that have not yet ratified the comprehensive global test ban treaty, including India and Pakistan, to do so.
It pressed Russia and the United States to agree on mutual steps "to take their nuclear weapons off hair-trigger alert" and launch negotiations on a new treaty aimed at slashing their strategic arms by at least half.
The new pact should include a legally binding commitment to irreversibly dismantle weapons that would be withdrawn, the commission advised.