Labour needs to listen to public opinion about foreign policy because the war in Iraq has led to "mistrust", a government minister has said.
Ms Harman said party members and voters were disillusioned
Constitutional Affairs Minister Harriet Harman said there was a "perception that we don't listen".
"Democratisation" of the Foreign Office could form a key aspect of the party's renewal, she wrote in the Sunday Times.
Ms Harman also called for an end to the convention where the prime minister can decide key foreign policy issues alone.
In doing so, she echoed indications from Chancellor Gordon Brown that he would be ready to consider scrapping the Royal Prerogative under which the prime minister is able to declare war without a vote in Parliament.
Her comments come as Labour debates its leadership and future approach.
Ms Harman - seen as an ally of Mr Brown as the prime minister's successor - said the Foreign Office needed to allow the public to feel "there is dialogue about vital issues".
"Could we open up foreign policy, for much broader public debate, rather than allowing it to remain the exclusive preserve of 'experts'?," she said.
Ms Harman acknowledged it would be wrong to have a referendum on every decision.
But she said: "Democratisation of the Foreign Office, as a key aspect of renewal, would see it catch up with the outward-looking culture that Labour has driven through the Department for Education and Skills, the Department of Health and the Home Office."
Ms Harman said the government's approach to foreign policy had become a "symbol of mistrust and division between the Labour leadership and the party and the government and the country".
She added: "The war in Iraq, our relationship with the United States, and our position on the conflict in the Lebanon this summer are all recurrent themes amongst those disillusioned with our party."