Money and thousands of pounds’ worth of drugs have been seized as an „indirect consequence“ of police vehicle checks during the coronavirus pandemic.
Senior police officers say it has been easier to catch criminals because there are fewer motorists on the roads.
Gwent Police have seized more than 300 vehicles and significant amounts of Class A drugs during checks.
Forces in Wales have been operating motorcycle „Covid patrols“ and have set up check points.
Gwent’s Deputy Chief Constable, Amanda Blakeman, said the force has found a wide range of drugs, from cannabis to cocaine, and organised criminals were now „much more prominent“.
She said: „We’ve seized thousands of pounds’ worth of cash, we’ve seized large quantities of Class A drugs, we’ve also seized other types of drugs.
„And we’ve seized and taken off the road 347 vehicles since the start of this.“
Officers discovered more than 2kg (4.4lb) of cocaine and £30,000 in cash in one vehicle stop.
Sgt Stuart Poulton, a police motorcyclist with 30 years of service, said: „Because we’re checking so many more now, we’re coming across more and more offences.
„They were probably always out there, it’s just that we’re detecting them an awful lot easier.
„It’s an indirect consequence of the lockdown.“
The work to police the lockdown is known as Operation Dovecote.
As part of the checks, Dyfed-Powys Police officers have found offensive weapons and drugs, and stopped a motorist with no licence or insurance who was towing a suspected stolen digger.
In Pembrokeshire, a man who travelled in a BMW from Cardiff to Tenby for a walk was arrested in Stepaside because police found he was wanted for recall to prison.
Police have been using roadside drug tests to catch motorists driving under the influence of cannabis or cocaine, in addition to tests for alcohol, and hundreds have been caught driving without a licence or insurance.
They include a man who said he was taking his children for a drive to get them to sleep – and was found to have no insurance.
Dyfed-Powys Police said a „substantial amount“ of cocaine was found in a car when it was stopped during a check in St Clears, Carmarthenshire, in April.
The force also discovered a suitcase containing 2kg of cannabis with a street value of £20,000 in the back of a van on the A40 near Haverfordwest in May.
Police road units are using automatic number place recognition (ANPR) to identify who motorists are, and where they may be coming from.
Ch Insp Martin Smith said it had been easier to track offenders who were moving in and out of Wales.
„Not all drivers are criminals but all criminals drive,“ he said.
„They are going to stand out more because there’s less vehicles on the road.“