Canada's opposition Liberal Party responded to criticism of its carbon tax plan on Wednesday, ahead of a looming election call, promising a total of C$900 million (US$849 million) in tax breaks and subsidies to farmers, loggers, fishermen and truckers.

The "green shift" carbon tax plan, the central election plank for the Liberals, will include tax breaks worth C$400 million for farmers and loggers who buy environmentally friendly machinery, said party leader Stephane Dion.