Witnesses are sought by police after a field was set alight causing thousands of pounds worth of damage to crops.
The incident happened in Great Melton between 9.30pm and 9.40pm on Wednesday in Burdock Lane.
The fire damaged between 1.75 and 2.5 hectors of wheat, valued at £4,500.
Police are keen to trace two men seen in the area around the time of the incident who may be able to help with the investigation.
The first is described as white, of slim build and in his mid 20s. He was walking on crutches and wearing a red t-shirt. The second suspect is believed to be in his early 30s with long hair and wearing a blue t-shirt.
Both men were seen with a white Citroen C1, possibly with an 05 number plate.
Anyone with information should contact Wymondham Police Station on 101 or call Crimestoppers on 0800 555 111.
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