A growing number of landlords are hiking rents of tenants they "know are really vulnerable," Social Development Minister Paula Bennett says.

Bennett today singled out a caravan park in her Waitakere electorate for what she called "absolutely sub-standard" housing.

"I think it is well over priced and I'm not an expert in housing markets," Bennett said.

"They insist that the rents are paid directly by Work and Income to get housing and you've got some of your most vulnerable that would not get tenancies anywhere else because they either have a poor record, or they're known as a high risk. That worries me."

Bennett's comments came in response to calls from Labour for a review of the accommodation supplement.

Labour's spokeswoman Annette King said the supplement, which is this year expected to cost the Government $1.2b, was "a major subsidy for landlords" and had not produced better housing or more access to housing.

"Some of it is absolutely appalling housing and landlords take whatever the accommodation supplement is and add it to their rent,’’ King said.

Bennett today said she had been looking at different ways of helping people towards home ownership.

As part of the Government's welfare reforms, compulsory payment of the supplement to landlords had been considered. That would often make landlords more confident about tenants, she said.

"We have come to the conclusion really that we would not be making redirections [of the supplement] compulsory and that they would be voluntary, but we may be able to loosen up the voluntary component of it so that it's easier for someone to say that they want to pay them."

Any changes to the supplement would be "incredibly complex" and could be very expensive or have a significant impact on the rental market.

Landlords hiking rents unfairly to the vulnerable should "have a good look at themselves," she said.

"Ask yourself whether you are giving a quality of housing that you, yourself would be happy to live in and I just think it means an element of fairness really, and that's what we ask of any New Zealander," Bennett said.

- © Fairfax NZ News