Siptu was urged yesterday to join an international campaign to get more workers into unions and combat a "race to the bottom" in employment standards.
Tom Woodruff, a union leader in the United States, said the experience in his country showed there was a direct link between growing inequalities in society and the declining influence of trade unions.
He told delegates to the Siptu conference in Cork that unions needed to form a global alliance to prevent exploitation of workers and secure acceptable standards of employment. But they had to do so from a position of strength, he said, and that required getting out and organising more and more members.
In a speech that drew a standing ovation from delegates, Mr Woodruff, who is vice-president of the Services Employees Industrial Union, said the "national disgrace" of Hurricane Katrina had opened many people's eyes to the reality of poverty in the United States.
"Hundreds of thousands of American people, mostly African-American and mostly poor, did not have income that allowed them to have cars or get transportation out of the disaster. Our union had more than 2,000 members in New Orleans and we are now in the process of trying to find them, [ as they are] spread out all across the country."
Mr Woodruff said that in some respects he felt he was standing before the Siptu delegates as the "ghost of their Christmas future", although he hoped this would not be the case. "I come from a labour movement that has failed in its core mission, which is to raise the living standards of working people and create some semblance of social and economic justice in society."
The United States was the richest country in the history of the world and was producing more and more all the time, and yet income was stagnant or declining for 60 per cent of American families. The top 1 per cent of earners owned more wealth than the bottom 95 per cent.
Average real wages in the US today were lower than in 1967. "After almost 40 years of working harder and producing more and more, the average worker is in the same place as 40 years ago. The value of the minimum wage is less than it was in 1956."
The average chief executive's salary in Japan, he said, was 11 times the average worker's salary. In Germany, it was 13 times the average, while in Britain the average CEO's pay was 24 times that of the average employee. "In the United States today, the average CEO earns 431 times more than the average worker."
At present, however, unions in the US did not have the power to effectively challenge such disparities. In the 1950s, 35 per cent of American workers were in unions.
"We're now down to 12.5 per cent, or one in eight workers. In the private sector, it's one in 12 workers.
"We simply don't have the strength to do what our members want us to do, which is to raise their living standards." Irish unions were in a much stronger position, but they could not afford to rest on it, he said.
