A three-day crackdown on cross-border drug, violent and acquisitive crime has resulted in 140 arrests.
Hertfordshire Constabulary teamed up with forces in London, Buckinghamshire, Berkshire, Oxfordshire and Surrey to tackle crime being carried out on main roads and motorways.
Officers in the joint operation - which ran between Tuesday, April 26 and Thursday, April 28 - made 141 arrests, with burglary, robbery and theft of motor vehicles among the suspected offences.
They also seized more than £14,500 in cash, along with 37 vehicles, 16 weapons and 48 bundles containing drugs.
Detective Chief Inspector Frankie Westoby, from Hertfordshire, said the operation should send a message to people who commit crime across county lines.
DCI Westoby said: "This operation is a great example of the successes that partnership working can bring.
"We had some fantastic results over the course of the three days and I’d like to thank everyone involved.
"I hope this sends a message to those who travel to commit crime that we will utilise everything at our disposal and work with our policing colleagues to catch up with you."
The forces used Automatic Number Plate Recognition Technology (ANPR) technology and police intelligence the target vehicles on arterial roads and motorways.
British Transport Police was involved in the operation to tackle criminals who might be exploiting the region's railway network.
The forces involved included Thames Valley Police and the Metropolitan Police.
Chief Inspector Rob Ranstead, representing the Met, said: "Organised crime, including county lines drug supply and criminals committing burglaries and robberies, are key drivers of violence in our communities.
"And offenders often exploit and target the vulnerable.
"Tackling violent crime and the supply of drugs is a top priority.
"The key aim of this operation was to stop drugs and weapons being brought onto the streets. Preventing these crimes, while also safeguarding vulnerable individuals on the cusp of violence, is paramount."
He added: "We will continue to deny the use of the roads and railway for violent and predatory people, drug dealers and those involved in county lines gangs and organised crime to operate."
Ch Insp Ranstead and DCI Westoby both urged members of the public concerned about crime to contact the police in their area.
This could help forces build up intelligence about how crime is committed.
They added that independent charity CrimeStoppers (https://crimestoppers-uk.org/) can receive reports anonymously.
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