The first incident occurred sometime during last Thursday evening and the early hours of Friday when two vehicles were broken into in Stepaside.
One of the vehicles, a Land Rover Freelander, had its rear offside window smashed and a black rucksack containing a quantity of cash, credit cards, cheque book and a Nokia-make mobile telephone stolen, while a car nearby was also entered and a mobile telephone, also a Nokia-make, taken.
In a second incident, a Peugoet car was broken into at Llandissilio during the early hours of Sunday morning.
Again, the rear offside window of the vehicle was smashed and this time a handbag with cash, cheque book, credit cards, driving licence and passport was taken.
Around the same time, another vehicle was broken into at Llanddewi Velfrey and a denim bag, together with cash, two mobile telephones, one of which was a Nokia make, stolen.
Police are appealing for anyone with any information to contact them and officers are also urging members of the public not to leave valuables visible in their vehicles, especially overnight.
"Other vehicles parked near the ones which have been broken into and did not have items visible from outside have not been entered," said the police spokesman.
A number of similar incidents have also occurred in the Crymych and Hebron areas and the police would like to hear from anyone who may have been offered the mobile telephones for sale.
Narberth police can be contacted on 01834 860389.