Arsonists have targeted two farms in Cambridgeshire and County Durham in separate incidents occurring in the space of just one week.
Firefighters tackled a farm blaze at around midnight on Wype Road in Eastrea on Thursday 2 April.
Cambridgeshire Fire and Rescue Service said the large barn and outbuilding fire was 'deliberate'.
The fire crew tackled the fire for four hours, returning to their stations at around 4:30am.
A Cambridgeshire Fire and Rescue Service spokesman said: “Crews arrived to find a barn and outbuilding on a farm well alight.
"Firefighters worked in sectors using hose reels and a jet to extinguish the fire before dampening down the area.
“All crews returned to their station by 4.30am. The cause of the fire is believed to be deliberate.”
Anyone with information should contact police by visiting www.cambs.police.uk to submit an online report or call Crimestoppers on 0800 555111.
In a separate incident, firefighters tackled a barn fire at a farm near Hartlepool. Police say it was started deliberately.
The incident happened at around 11pm on Sunday 29 March, at Thorpe Bulmer Farm in Hart Village.
The blaze left major damage to a barn and the contents within, Cleveland Police said.
Cleveland Fire Brigade added that it was 'disappointing' to see arson attacks during a time when 'we all need to be coming together'.
Steve Johnson, Area Manager Prevention for the service, said: “We need the public’s support now more than ever. Our resources need to be available to respond to any fires in the home and support with humanitarian aid for vulnerable people in our communities.
"We are pleading with the public to support us to remove arson from our neighbourhoods. This is an ideal opportunity for communities to get behind us on the zero tolerance to arsonists.”
Officers are urging anyone with information to come forward by contacting Detective Constable David Angel from Hartlepool CID on the non-emergency number 101, quoting event number 49022.
What can I do to cut the risk of arson?
Whilst arson attacks on farms and small holdings may be difficult to eliminate, the NFU has provided number of simple precautions can substantially reduce the risk.
• Remove hay and straw from fields as soon as possible after harvesting
• Store bales separately from buildings, machinery and chemicals
• Make stacks a reasonable size and space them at least 10 metres apart
• Site stacks away from paths and rights of way
• Keep petrol, diesel and other fuels (including gas cylinders) stored in secure areas
• Keep fertilisers and pesticides under lock and key
• Dispose of refuse safely on a regular basis
• Ensure fences and gates are in good condition and check them regularly
• Install intruder sensors and security lighting
• Prepare a fire routine and action plan and make sure all farm staff know what to do
• If a fire breaks out, call the fire and rescue service without delay.
