Dog walkers who do not have the evidence they can pick up dog waste could be fined £100.
A council in Nottinghamshire has authorised wardens to be able to challenge dog owners on if they have "the means" to pick up dog poo.
If they can't prove this, they can be issued with £100 spot fines, which could increase to £1,000 if they fail to settle the fine.
Dog owners have criticised the measures as penalising responsible pet owners,
Dr Ed Hayes, head of public affairs at The Kennel Club, said: “An important aspect of being a responsible dog owner means cleaning up any mess their dog leaves behind and having a supply of dog waste bags with them.
Dog file photo Steve Parsons
“However, whilst we support proactive efforts on behalf of local authorities to encourage owners to pick up after their dogs, we are concerned that these measures, suggested by Rushcliffe Borough Council, could see otherwise conscientious owners penalised unfairly, for instance if they have already used the necessary bags, or given a spare to someone else, as encouraged by Green Dog Walker schemes.
“Local authorities may wish instead to consider alternative measures, such as introducing a clause which provides an exemption for those who have run out of bags but are able to prove that they were in possession of and made use of these during their walk.
"However, it is essential that any plans are effectively communicated to local residents to ensure they have an excess supply of dog waste bags with them.”
The measures have been introduced recently by Rushcliffe Borough Council in Nottinghamshire.
Similar rules are already being enforced in Somerset, Devonshire, Lancashire and Derbyshire.
A spokesman for Dogs Trust said: “Everyone wants to enjoy public spaces free from dog mess. However, we don’t believe punishing the masses for the actions of a few is the best approach.
“Encouraging dog owners to pick up after their dog is something Dogs Trust continues to campaign for and we welcome any initiative introduced by a local authority to discourage dog fouling.
“However, we believe education and the encouragement of responsible dog ownership is much more effective than handing out fines, specifically if dog owners are confused and unaware of the PSPO.”