"While it isn't a dramatic increase, it's still enough to cause concern. People need to make sure they lock their doors and close their windows while they are at work. They also need to make sure they report any suspicious behaviour to police and talk to their neighbours.
"These three young men appear they are trying to blend in, by disguising themselves as construction workers."
Householders are also being targeted by a bogus Fletcher earthquake assessor.
Police are unsure if the conman is linked to the recent theft of Fletcher clothing, a red zone pass and identification from five parked cars in St Albans.
Rebuild Christchurch has posted a message on its Facebook page warning residents about a man, named Jay, who claims to be from Fletcher Construction.
The message said that Jay, who is calling residents, claims that he and his team from Fletchers will be in the neighbourhood in the coming week to do inspection before the start of earthquake repairs.
It is understood this man is asking questions about people's houses, including when they will not be home to make sure his team doesn't miss them.
Mr Bothamley said police are aware of it and while there have been no offences confirmed, the more people that know about it, the better.
"People shouldn't give out any personal information over the phone. If he does call, make sure you ask for his contact details, including a phone number, then call police. He is preying on people and going out of his way to find out of everything about people's houses so he can plan a burglary."
Fletcher Construction spokesman Barry Akers said the firm is aware of the imposter.
"Every employee has an identification card or tag that they can show people. If they don't have this, then don't let them into your house. All we can do is make people aware of it. It isn't someone known to us."
Meanwhile, cars parked on the road side and in driveways in south Christchurch are being targeted by youths.
A number of vehicles have been broken into over the last few weeks in this area.
Money, iPods, GPS units, laptops, cellphones and other electronic equipment have been stolen.
Mr Bothamley said it's a case of people making sure they hide their valuables and lock their cars at night, even if they are parked in their driveway.
"Each week we normally receive between 20 and 40 reports of cars being broken into and items stolen. In the last week we've noticed an increase. A lot of this type of crime is generally committed by youths. It's about being vigilant. If people see any groups of youths hanging around the area, call police."
