Farmers in mid Wales have refused permission for SAS troops to train on their lands in retaliation for the armed forces buying meat from overseas.
Farmers in the Brecon Beacons have said the request for use of their land from the Ministry of Defence (MoD)was an insult when it was not supporting meat producers in this country.
"
The only weapon that farmers have is to stop the MoD going on their land
"
Peredur Hughes, NFU Wales
The Army wants to use a 25-square-mile segment of the Beacons to stage a week-long training SAS exercise in October.
The MoD had written to landowners in the area for permission, but some have said no as a means of protesting against the Army's food-buying practices.
National Farmers Union in Wales chairman Peredur Hughes said: "Unfortunately, they are only buying 2% of their lamb from the UK which to my mind is totally unacceptable.
"Quite frankly, farmers are very angry about it.
"The only weapon that farmers have is to stop the MoD going on their land."
The refusal by the farmers is a repeat of an unsuccessful protest last year to persuade the Army to buy British produce.
The MoD said its food supply contractor was required to secure food at the best value for money.
However, it also had to give consideration to locally-produced supplies.
SAS training
The rugged terrain of the Beacons is perfect training ground for soldiers undergoing military instruction.
The planned exercise in October will involve 170 serving or potential SAS fighters being pursued by a "hunter" force.
Up to 300,000 soldiers regularly use the Eppynt army ranges at Sennybridge in Powys.