Retailers, seeking to cut costs in the economic downturn, need to continue investing in environmental sustainability if they want to retain customers, according to a report published on Wednesday.

Havas Media, opening the annual World Retail Congress, said a survey of 20,000 consumers in 10 countries found that 80 percent would reward brands that adopted sustainable practices, while 72 percent would punish those that did not.

Some 48 percent of the people surveyed also said they were prepared to pay a little bit more for sustainable goods.

The survey found retailers scored highly in such areas such as responsible marketing, fair prices and sale of healthy products, with companies like Wal-Mart in the United States, El Cortes Ingles in Spain and Marks & Spencer in Britain identified by consumers as leaders in the field.

However, store groups performed less well in areas like packaging, recycling, sourcing of goods and fair pay.

(Reporting by Mark Potter; editing by Karen Foster)