This comes as councillors yesterday unanimously approved $273,050 for a dedicated search-and-destroy and surveillance programme to control the pests in Otago.
But councillors were warned the spend would not be a one-off cost and to expect to have to continue the fight to control Otago's wallaby population ''in perpetuity''.
After the council meeting, director of environmental monitoring and operations Scott MacLean said the location of recent sightings of wallabies in Oamaru and in Central Otago suggested someone might be intentionally releasing them.
''Quite a number of the sightings were right in the Oamaru township. One was literally up someone's driveway.
''It most likely didn't get there naturally,'' Mr MacLean said.
A female wallaby shot by a member of Maniototo Pest Company in Kyeburn on Monday night could have also been introduced intentionally.
He warned anyone releasing the wallabies that what they were doing was illegal and they would face the consequences if they did not stop.
''Wallabies have a significant impact on the rural economy.''
Anyone found deliberately releasing wallabies, which is in breach of the Biosecurity Act, could be imprisoned for up to five years, and/or fined up to $100,000.
At the meeting, Cr Graeme Bell raised the importance of working with Environment Canterbury to control the population in the area just across the border from Otago.
Mr MacLean said it was working very closely with its Canterbury counterparts.
The main ''highway'' for wallabies crossing in to Otago was the dams. Meridian Energy had installed some fencing in an attempt to restrict numbers coming south, Mr MacLean said.
''But no-one has yet successfully come up with a wallaby deterrent suitable for a dam.''
Advice from Australia had shown a plan to use cattle stops would not have worked.
He said the money would not provide a quick-fix.
''It's not a one-year programme.
''I think this will be ongoing in perpetuity,'' he told councillors.
Cr Gerrard Eckhoff made a joking reference to Donald Trump's proposal for a wall on the Mexico border as he praised the plan.
''I'm very pleased to see this.
''The last thing land-owners need is another pest problem like rabbits and possums,'' Cr Eckhoff said.
Rather than building a wall, the money would go towards ''regular, structured search-and-destroy operations and ongoing surveillance'' to deal with any incursions, Mr Bodeker said in his report seeking approval for the spending.
The bulk of the money, $198,050, would pay for two fulltime staff and some auxilliary staff, but the money, to come from council reserves, would also cover bait stations, specialist contractors and helicopter hire.
Mr Bodeker said educational field days on the wallaby problem would be held in Weston, Naseby/Ranfurly, and Tarras within the next couple of months, and council staff would be on the ground to monitor areas where wallabies had been seen.
