LONDON, England (CNN) -- In 1996 U.S. talk show host Kathie Lee Gifford burst into tears on TV when human rights campaigner Charles Kernaghan told her she had a clothing line manufactured by children in Honduras.

The presenter became an anti-sweatshop campaigner.

Pressure groups now come in different shapes and sizes. Some use the courtrooms while others favour mass protests.

The main aim for them all is to hit companies where it hurts most -- tarnishing their image and therefore hitting their pockets.

In the clothing industry, which accounts for much of the world's sweatshop labour, big retail firms used to say they bought from middlemen, so they had no way of knowing where the clothes were made or the working conditions of those making them.

Now many firms are working with non-governmental organisations and accounting firms to check the conditions on their subcontractors' premises.

The U.S. government in particular is being pressed to make companies accountable for the labour practices of their subcontractors.

Changes 'superficial'

However, Jeffrey Ballinger, a Harvard researcher and director of pressure group Press for Change, told CNN that despite the campaigning, firms were still doing too little to improve the situation on the ground.

"The changes made to improve working conditions amount to window dressing and fail to address the fundamental problems. The real battle is on the ground between workers and contractors," he said.

The UK pressure group Labour behind the Label (LBL) said any changes made by firms were "superficial" and that there had been no improvement in fundamentals such as providing workers with a living wage and allowing them the right to organise and join unions.

A member of LBL's co-ordination team told CNN that the codes of conduct introduced by most firms for their subcontractors did not address these major issues.

Many campaigners even question the economics of outsourcing production and point to companies such as Spanish clothing firm Zara.

It not only sells clothes but also designs and makes them. It has never run an advertising campaign yet it has about 1,000 shops worldwide.

As clothes are made in Spain, transport costs are low, it does not overstock and can produce small quantities to test the market.

Its success has led to it being described as "possibly the most innovative and devastating retailer in the world," by LVMH fashion director Daniel Piette.