Environmentally friendly products and services are often more expensive than conventional lines and could be the first to go as families review their household budgets, they say.

Research has found that concern over the environment is not translating into sales, and is less likely to do so as consumers worry about how the deteriorating economy will affect them.

Being environmentally responsible was one of the least important drivers, according to the findings of a survey of 800 people by Blue Marlin, a design agency.

Even among self-styled green consumers, only a small proportion are motivated by environmental product claims.

Overall, two thirds of respondents said environmentally friendly products were overpriced, rising to 72pc among families with children.

The head of strategy at Blue Marlin, John Matthews, said shoppers bought green products only if they delivered "tangible benefits".

"Saving the environment is a happy outcome, but it's not the primary driver," he said.

He said many products failed to persuade shoppers of these benefits and instead had relied upon their emotional commitment to the "green movement".

"It's not enough to rely on the faith of consumers.

"Brands can't demand action from consumers, but they can help [them] to act.

"If a brand tells you you are going to hell if you don't buy it, then they probably won't buy it."

Mr Matthews said calls to his agency from companies looking to incorporate carbon offset logos or environmental claims on packaging had dried up.

Late last year another company, Mobium Research, which tracks attitudes of 1700 consumers, found that the number of people who said they were willing to pay a 25pc premium for a product that was "made in an environmentally friendly manner" had fallen from half in 2007 to a third.

It also found that almost nine in 10 consumers distrusted green claims.

Annual spending on green-leaning products is forecast to top $22 billion by 2010.

Australia's largest retailer of green products and services, Neco said it had yet to witness a sales slump.

Its managing director, Julian Smith said he was planning for growth this year, and had just opened a superstore in Melbourne with one planned for Sydney.

"Green products have a good message to sell … products like solar panels and water tanks can save you money over time.

"We are putting out the message that you can save money and be green."