More than a million British motorists are now boycotting Esso over its opposition to climate change agreements, Greenpeace claimed last week.
The number of petrol buyers who say they regularly use Esso pumps has fallen by about a quarter since the boycott began last year, according to new figures from Mori Social Research.
Five per cent of motorists polled said they already boycott Esso, and nearly half said they would if asked to do so by environmental groups.
Twenty-six per cent of petrol buyers said they regularly used Esso pumps last year. That figure has now fallen to 19 per cent. The boycott was launched last year after Esso was credited with bringing about the US withdrawal from the Kyoto global warming treaty.