Former UN weapons inspector says UK will not be more protected if it extends life of Trident, at a cost of £100bn

Former UN weapons inspector Hans Blix has said it is time for Britain to relinquish its Trident nuclear programme.

Speaking at the Hay literary festival, the Swedish international lawyer who led the hunt for weapons of mass destruction in the lead-up to the Iraq war, said he did not see how the UK would be any more protected if it extended the life of the nuclear programme – at an estimated cost of £100bn.

Delivering the 2013 Joseph Rotblat lecture to an audience of 1,600 festival goers, Blix said Washington "was not pushing for this costly rearmament" and asked if Trident was "required to protect UK independence or UK pride".

"Japan and Germany seem respected … even without nuclear weapons," he said.

Asked if the UK should abolish its independent nuclear deterrent, he said "it would be a big gain" to Britain if it did, adding: "I know that the British military are not very keen on it. I don't think Britain would be more protected by [Trident] and Germany and Japan seem to be managing without them [nuclear weapons]."

Speaking a decade after the start of the Iraq war, Blix said he had no evidence that Tony Blair and President Bush acted in bad faith over their decision to go to war, but simply made an error of terrible judgment. But he said Blair's policy of liberal intervention, set out in a keynote foreign policy speech in Chicago in 1999, had undermined international law which had implications for current crises.

He said: "The risk of large wars may have gone but the risk of armed intervention remains. In most cases, say, North Korea, Syria … the cost of armed interventions in terms of lives and resources have limited temptations.

"But it may be asked what weight does international legal rule have per se? We have to admit that in the current cases of Iran and Syria there is astonishing little attention paid to the legality of armed intervention."

He warned that current threats by the US and Israel of armed action against Iran were not based on international legal structures adding, "we hear about possible unilateral armed action to eradicate what: intentions, that may or may not exist."

Blix, who is currently advising the UAE's of its nuclear power programme, also feared that the post-cold war nuclear weapons disarmament process was in "stagnation" and had stalled in part because of the financial crash adding, "The Geneva disarmament conference continues its decade long coma."