Tributes have been paid to the antiwar activist Walter Wolfgang, who has died aged 95, with many remembering a “committed fighter for peace and justice” and a lifelong socialist who “always spoke truth to power”.

Wolfgang, a Jewish refugee from Nazi Germany, joined the Labour party in 1948 and was a founding member of the Campaign for Nuclear Disarmament, remaining active in the organisation until his death. He was propelled into the public eye in 2005 after heckling Jack Straw at the Labour conference.

After apparently shouting “Nonsense” during the then foreign secretary’s speech on Iraq, as Straw spoke of “nation-building from a violent past” to justify keeping British troops in the country, Wolfgang was manhandled out of his seat by security.

He was briefly detained under terrorism laws, before returning to the conference the next day amid a flurry of apologies. “When you have an international debate that does not deal adequately with the international issues of the day, the least you can do, if someone is talking nonsense, is say so,” Wolfgang said.

Rest in peace Walter Wolfgang🌹



Socialist, refugee from Nazism, long-time Labour Party member and opponent of the war in Iraq. pic.twitter.com/nteoRDsv76 — Tribune (@tribunemagazine) May 29, 2019

He later served on Labour’s national executive committee and last year was made a patron of the Stop the War coalition, saying at the time: “We can win. We shall overcome. Thank you for this huge honour.”

Wolfgang was also recognised for his years of dedication to the Labour party in 2018. He said he did not deserve the merit award because “I merely did what I had to do”, in a speech that also called for full employment, public ownership and extending trade union rights, a peace policy based on negotiations, global nuclear disarmament and free discussion on justice for Palestinians.

A former Labour candidate in Croydon and delegate for the constituency party in Richmond upon Thames, Wolfgang had long called for greater democracy within the party and supported Jeremy Corbyn’s campaign to become leader in 2015.

On Wednesday evening, the Labour leader led tributes to the “courageous moral leader” and tweeted a photo of them sat together, writing: “Deeply saddened to hear that my old friend Walter Wolfgang has died. Walter escaped Nazi Germany and has campaigned for peace and socialism ever since, including his passionate opposition to the Iraq war. Yesterday, we said our goodbyes. He will be greatly missed.”

CND tweeted: “We’re very sad to learn that Walter Wolfgang has died. Walter was a founding member of CND and on the committee which organised the first Aldermaston march [from London to the atomic weapons research base in Berkshire]. Active with CND until the very end, we say thank you for the enormous contribution Walter made to peace and disarmament.”

Unite general secretary Len McCluskey tweeted: “I’m saddened to hear of the death of Walter Wolfgang. 70 years a Labour Party member, lifelong socialist and man of peace who had no trouble calling out the Iraq war lies.”