The congress claims that the UK government is "out of step" with the views of workers on the matter.

On Tuesday, Foreign Secretary David Miliband said he was saddened by the boycotts of economic and academic events, as well as cultural events which seek to increase understanding between people.

"Such boycotts would, I believe, obstruct opportunities for co-operation and dialogue and serve only to polarise debate further," he added.

But the assistant secretary of the Scottish TUC, Mary Senior, said: "Rather than expressing his dismay to us, the Foreign Secretary should be expressing his outrage in the strongest terms to the Israeli government for its attacks on the people of Gaza, for the growing Israeli settlements in Palestinian territory and for the ongoing breaches of international human rights laws."

The STUC plans to contact Minister for the Middle East Ivan Lewis next week, as well as to approach Miliband in order to "impress upon him the case for sanctions against the state of Israel". Mr Lewis is this week meeting union representatives to make clear the government's firm belief that calls for boycotts of Israel cannot - and do not - contribute to peace.

Mr Miliband said: "British people of all backgrounds are distressed and frustrated by the Arab-Israeli conflict.

"Many wish to take action to advance the goals of peace and justice - a response I understand and share intensely.

"But I am saddened when this proactive energy is channelled into boycotts which would only make it harder to achieve the peace that both Palestinians and Israelis deserve and desire."

He went on: "Rather than seeking to boycott, I urge the unions to help find a shared solution to common challenges, and I am encouraged that they are ready to do so."