Consultants are being brought in to work out whether the spread of shared student housing in Bath could be restricted by planning laws.

A national pressure group representing landlords claims that such a move would drive up rents while cutting house prices.

The 15,000-strong Residential Landlords Association is urging Bath and North East Somerset Council to abandon any interest in using the planning system to discourage the conversion of family homes into student accommodation.

But politicians in Oldfield Park, where student houses dominate some streets, say the organisation is being alarmist.

Councillors from both the Liberal Democrat and Conservative parties have backed the idea of investigating the use of what is known as an Article 4 Direction to force landlords to apply for planning permission for such conversion work in certain parts of the city.

Such a direction would mean planning consent is needed for developments that do not normally need approval, and could help combat the so-called studentification of areas such as Oldfield Park.

The Coalition Government scrapped Labour's plans for national moves to restrict houses in multiple occupation soon after taking power.

At the moment, planning permission is not needed to convert a property from use as a single unit to become a house in multiple occupation (HMO) with between three and six tenants who are not related.

A B&NES spokesman said its core strategy blueprint, which has just completed a round of public consultation, "included specific policies which are directed at ensuring that a balance is struck between the aspirations of the universities and impacts upon the wider community."

He said: "Council officers are in the process of seeking expressions of interest from planning consultants on its framework which will establish both the costs and the timeframe for the delivery of a potential Article 4 Direction to control the further establishment of HMOs in the city."

Oldfield Park councillor Will Sandry (Lib Dem, Oldfield) said he thought the RLA's claims were "quite alarmist".

He said: "The Bath area has a really resilient property market and it's important to say that anything that is done would not be retrospective.

"We realise that there is a need for HMOs, but a significant number of my area's residents want some sort of restriction."

He said something had to be done to protect family accommodation, and acknowledged that more purpose-built student blocks may be needed both on campus and elsewhere in the city.

The RLA says that in other areas where extra restrictions have been imposed, owner-occupiers have seen the value of their property fall by as much as a third because of the perception that they will never be able to get planning permission in the future for a change of use.

Its chairman Alan Ward said: "Small houses in multiple occupation have an important role to play in housing the increasing number of students attending university, and many young professionals, such as nurses, for whom home ownership is simply unaffordable.

"Actions by the council to restrict the availability of much-needed housing for mainly young people will not only deny them the chance to live where they want, but will also drive up rents while at the same time significantly cutting house prices in the designated area.

"Many owners will be worried at such a steep drop in the value of their single biggest asset."

Estate agent Carey Gilliland, a partner in city firm Madison Oakley, said it was crucial to remember that HMOs were not just used by students.

"There is a whole group of folk – from professional people to low income families – who rely on HMOs, and they don't need any more problems in their search for housing."

He said several house sales fell through when the old Labour government looked like bringing in new legislation aimed at curbing such conversions.