The RSPB and Greenpeace have reported at least three illegal peat burns in Cumbria since the practice was banned last year.
The Government introduced new rules last year that banned the burning of heather and other vegetation on blanket bog habitats.
These are areas of deep peat in Special Areas of Conservation or Special Protection Areas unless a licence has been granted or the land is steep or rocky.
The Government said that no licence was granted for the last burning season, which ended on the 15th April.
The Moorland Association, which represents moorland landowners, say that careful burning has been a traditional part of moorland management for more than a century.
However campaigners argue that the practice is used to aid grouse shooting by destroying vegetation that the birds can hide in.
Peat soil is an important carbon sink. The Government called areas of peatland England's "rainforests" when they introduced legislation last year.
When vegetation on the peat is burned, carbon that has been stored for thousands of years in the soil is released into the atmosphere.
According to the Cumbria Wildlife Trust, there is an estimated 88,000 hectares of peatland soil in Cumbria.
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