Twenty-two horses have been impounded in Ashington and Newbiggin-by-the-Sea.
In the early hours of Tuesday a team of bailiffs removed the horses in a bid to tackle the growing problem of illegal grazing.
Coun Ian Swithenbank, policy board member responsible for streetcare and environment at Northumberland County Council, said: “As a result of individuals not following instructions and notices from the council about the illegal tethering of horses on council and privately owned land, in the early hours of Tuesday morning, 22 horses were removed and impounded.
“The council has been clear in its intentions from the start that this action would be taken if necessary.
“We have worked with partner agencies including police, community organisations and housing landlords to ensure horse owners have been provided with the correct instructions and information regarding illegal grazing and tethering of horses.”
There were no injuries or animal welfare issues and no disorder or arrests made during the operation.
The bailiff company will hold the horses for a specified period of time, after which attempts will be made to re-home them.
Anyone now looking to have a horse returned will face costs.
The county recently announced details of two authorised horse-grazing sites in Newbiggin-by-the-Sea and work is on-going to identify another in Ashington.
Coun Swithenbank urged horse owners to take up the offer of grazing their animals legally on the county’s designated sites.
Chief Inspector of the RSPCA Michelle Charlton said: “The codes of practice for the welfare of equines suggest tethering is only used for short term projects when under veterinary supervision.
“We have tried, along with other welfare organisations, to educate and encourage responsible horse ownership.
“Where we are failing then action needs to be taken.”