Police made 44 arrests and seized 26 vehicles as part of a crackdown on cross-border crime in Hertfordshire.
Criminals in Hertsmere and Watford were among those targeted in week-long action with the Met Police, which also patrolled Harrow and Barnet.
The campaign earlier this month saw dozens of arrests for crimes relating to drugs, vehicle thefts, weapons and affray.
Hertfordshire Constabulary says 12 lost or stolen vehicles were seized and 14 were taken for traffic offences. Officers also recovered a machete, kitchen knife and baseball bat.
PC Brad Glover said: “This operation has reaped great results and will hopefully send a clear message that Herts is an area to be avoided.”
The operation targeted those involved in serious and acquisitive crime and involved “very intensive joint activity” with the Met, he added.
It comes amid recent criticism that Herts Police is failing to tackle vehicle theft – with 1,201 cars stolen in the county in 12 months but just 2% resulting in charges.
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