The number of arrests for theft in Ceredigion, Carmarthenshire, Pembrokeshire and Powys has risen by a third in the last five years, new figures show.
In August, former Home Secretary Suella Braverman said every theft must be investigated, adding it was "completely unacceptable" that some crimes have been effectively legalised.
Last month, police, retailers and the UK Government launched the Retail Crime Action Plan to improve response times to retail-related crime, including theft and shoplifting.
Home Office figures show 603 arrests were made for a theft offence by Dyfed-Powys Police in the 12 months to March.
This was up from 462 in 2017-18, meaning the number of theft arrests has risen by 31 per cent in the last five years.
The rise in arrests bucks the 12 per cent decrease in the number of offences logged, from 7,754 in 2017-18 to 6,807 last year.
Increasing arrest figures contrasts the trend across England and Wales, where the number of arrests fell by 37 per cent to 88,914 over the same period.
Ms Braverman told BBC Breakfast: "There is no such crime as minor crime – whether it's phone theft, car theft, watch theft, whether it's street-level drug-dealing or drug use, the police must now follow every reasonable line of inquiry."
Chief Constable Amanda Blakeman, council lead for acquisitive crime at the National Police Chiefs' Council, said: "We recognise how invasive and traumatic it is to be a victim of burglary and theft, and we are already investing significant resources in preventing and investigating serious acquisitive crime.
"Burglary levels have fallen by 51 per cent over the past decade due to this increased investment, and all police forces in England and Wales are now attending every home burglary.
"It is for individual Chief Constables to manage demand within their force and prioritise their resources, drawing on the support of national standards and guidance.
"We do not consider anything to be 'low-level' crime. Each and every crime will have an impact on victims, and this should never be underestimated."
Charge rates for thefts are very low, with just 4.4 per cent of offences with a recorded outcome resulting in a charge or summons nationally in the year to March.
In Dyfed-Powys, 8.1 per cent led to a charge or summons.
A Home Office spokesperson said: "Since 2010, our communities are safer, with theft offences down by 47 per cent and robbery down by 81 per cent.
"We have also delivered more police officers in England and Wales than ever before and the police have committed to attend all home burglaries and pursue all reasonable lines of enquiry to ensure more crimes are solved and public confidence is improved."