Farm vehicles will be targeted in the new campaign
Farmers are being targeted in a new road safety campaign launched by Dyfed-Powys Police.
Officers say they will be targeting tractors, trailers and other agricultural machinery used on public roads.
The initiative follows concerns about the number of accidents involving farm vehicles at harvest time last year.
The owners of vehicles with dangerous defects are being warned they face prosecution, but farmers' leaders have urged officers not to take a heavy handed approach.
Where farmers are stopped by police for minor defects we would ask they are treated in the same way as any other road user
FUW executive officer Peter Davies
A police spokesman said: "Particular attention will be paid to road safety issues which include lights, breaks, steering, tyres and oil or fuel leaks."
Officers will also be looking for unguarded sharp or protruding parts such as bale spikes.
Vehicles found to be a danger could be prevented from completing their journey.
"There is also concern about the manner in which agricultural vehicles or convoys of such vehicles are driven on the road," added the spokesman.
"Where applicable advice or if necessary prosecution for inconsiderate driving will be initiated."
The Farmers Union of Wales (FUW) says it welcomes the campaign as long as farmers are treated fairly.
The FUW's executive officer for Carmarthenshire Peter Davies said: "This is reasonable so long as farmers are treated fairly and police do not take a heavy handed approach.
"Where farmers are stopped by police for minor defects we would ask they are treated in the same way as any other road user."
Chief Inspector Roger Hughes, who is in charge of police operations in Pembrokeshire, said reducing accidents on rural roads was a key priority.
"Road safety is an area of priority highlighted by the Pembrokeshire Community Safety Group," he said.
"It is one of our policing objectives.
"We will be working with all agencies and partners to achieve this objective and improve the overall road safety for residents and visitors.
"This should be seen as an opportunity to prevent serious injuries on our roads."