Fences installed to deter drug users gathering under a Cardiff railway bridge could demonise people who need help, a homeless charity has warned.
The fences have been put up in Lloyd George Avenue, near the city centre.
The Welsh Government took action after complaints by nearby residents about drug dealing and discarded needles.
Richard Edwards, chief executive of the Huggard charity, said such "hostile architecture" would only disperse antisocial behaviour to other areas.
He said he had "huge sympathy" with local residents but added the underlying issues about addictions needed to be addressed.
"We need to be looking to be a city that provides safe spaces for people who are experiencing rough sleeping and problems that are keeping people on the streets," he told the Local Democracy Reporting Service.
"Providing hostile architecture in some ways demonises people who have found themselves in that position and doesn't help them move forward."
Local resident Rachel England, 34, regularly uses the underpass and said she often came across the same homeless people there.
She said: "In my experience, they've always kept themselves to themselves.
"I've never felt threatened and I've never seen any evidence of antisocial behaviour beyond the odd bit of littering.
"Blocking off this space - one of the few remaining dry spaces in Cardiff - seems especially callous when authorities are cracking down so hard on the homeless population in the centre of the city.
"Where are they supposed to go?"
A Welsh Government spokeswoman said: "The intention of this was not to remove opportunities for shelter but to improve safety for everyone.
"We are committed to supporting rough sleepers off the streets. We are investing £30m this year and the next to tackle homelessness and rough sleeping."