The poll found that the proportion of companies at which environmental issues appear on board agendas had slipped from 64 per cent last year to 56 per cent.
Companies at which no boardroom time is spent on 'green' matters rose from 31 to 44 per cent.
Only a quarter of directors said their companies had formal environmental policies.
Directors of construction and mining companies are most likely to spend time on environmental issues (68 per cent), followed by directors of manufacturers (56 per cent), distribution (51 per cent) and business and personal services (47 per cent).
The boards of small companies spent least time on the environment - 62 per cent of directors said they did not discuss green issues at all, against 50 per cent in 1992.
The main reason given by directors for focusing on the environment has changed from compliance with domestic and European legislation to social responsibility.Reuse content