DOG owners have been warned to be on their guard after a series of suspicious activities across the area.

Royston resident Julie Arnold, of Mill Road, was at work when her 18-year-old son answered the door to two women claiming to represent the RSPCA.

She said: “They heard our dogs barking and asked my son what breed they were. They kept asking to come in and if the dogs were kept crated overnight. I’m glad I told my son not to let them in.”

The women had been seen in the street for several days in a van displaying a makeshift RSPCA logo.

When Mrs Arnold called the RSPCA to enquire why they had made the visit, they assured her a legitimate officer would have been required to leave a calling card. No such card was left.

Another man, who wished to remain anonymous, claimed to have seen men walking down his street whistling and writing down the addresses of homes with dogs in them.

He has also had a similar experience to Mrs Arnold.

“Someone knocked at our door and, when my wife answered, they saw our Labrador in the hallway. Then they just left without saying a word,” he said

A spokesman for the RSPCA said: “It is important that dog owners take the proper precautions in order to keep their pets safe. Any incidents of actual or attempted dognapping should be reported to the police immediately.”

More than 3,000 cases of dognapping were reported in England last year. It is believed some of the animals are stolen to order, some of which can be worth more than £2,000.

Police have said there is not enough evidence to launch an investigation at present.

But anyone with information can contact the police on their non-emergency number 101 or call Crimestoppers anonymously on 0800 555 111.