Development charity War on Want joined with the Trades Union Congress on 1 May to launch a joint campaign on reforming world trade.
Supporters are being asked to email Patricia Hewitt, secretary of state for trade and industry, to demand a fundamental reform of the World Trade Organisation.
The charity wants the WTO's commitment to liberalisation and deregulation to be replaced by a pledge to enhance the public interest, especially for the poor, workers, the environment and human rights.
It also wants more transparency at WTO meetings and an end to informal negotiations.
Chief executive Louise Richards said: "It seems incredible these days to label such countries 'developing' when the present set of trade rules allows for anything but."
Other groups such as Oxfam (left) are campaigning for WTO change.