The government says first-time buyers will not be priced out
Second-home investors should be stopped from buying properties in so-called "eco-towns", it has been claimed.
Peter Bolton King, chief executive of the National Association of Estate Agents (NAEA), said planning conditions could be needed to ensure local buyers were not priced out of the market.
The government insists that between 30% and 50% of homes in all the new towns will be affordable.
But Mr Bolton King said "careful thought" was needed to ensure local people could afford to move into them.
"There's almost bound to be high demand. Are they (planners) going to say a percentage of these properties are only available to people living in the local area?
"That debate has still got to be had because I personally would like to see help given to local people who are looking for a home.
Careful thought has to be given as to whether there needs to be planning conditions to stop properties being bought up as second homes
Peter Bolton King
National Association of Estate Agents
"It would enable them to get onto a property ladder rather than people from outside saying, 'that's a nice place to live'."
Under government plans the current list of 15 sites will be narrowed down to 10 after a second wave of consultation.
Protesters and groups such as the Campaign to Protect Rural England (CPRE) fear the towns could be built on greenfield sites, where previous housing plans have already been rejected.
There are also concerns the new towns could become little more than commuter suburbs.
Despite all the protests, the NAEA believes "eco-town" homes will prove popular.
Mr Bolton King said towns like Middle Quinton, a proposed 6,000-home development six miles from Stratford-upon-Avon, could become sought-after locations.
"If you take the Stratford area, you've got a situation where it's high priced properties, there's therefore a real problem with a shortage of affordable property," he said.
"There could be an argument that says there's going to be opportunities for people to get onto the property ladder in a nice area that's convenient."
Campaigners claim the towns would put huge pressure on local services
Demand could also be high from buy-to-let investors, he added.
"At the moment in many areas, because people aren't buying properties, there's been a big increase in people wanting to rent and we're finding there's a shortage of property.
"I think very careful thought has to be given as to whether there needs to be planning conditions to stop properties being bought up as second homes," he said.
Richard Copus, from the Devon branch of the NAEA, said he thought spiralling gas and electricity bills would encourage many people to buy better insulated eco-homes.
"With the way everything is going at the moment with high fuel costs, any new home that will lead to a reduction in bills will lead all the others," he said.
He said buyers would be willing to pay more for eco-homes if they saved money on bills in the long run.
Continued car use
And he agreed measures should be considered to stop investors buying many of the properties.
"I would be surprised if there weren't restrictions on them to stop second home ownership," he said.
A key part of the "eco-town" plans is meant to be that residents use public transport, walk or cycle, rather than using their cars.
But Mr Copus said it was inevitable that people living in new towns would continue to use their own vehicles roads.
"We're always going to get commuters, at the end of the day I think we've got to accept that," he added.
A spokesman for the Department for Communities and Local Government said the government was committed to ensuring first-time buyers and people on low incomes could afford to move to the proposed new towns.
He added initiatives such as shared equity schemes would be available to help people get onto the property ladder.
BBC News will be examining on Wednesday which firms would build "eco-towns" in a time of a declining housing market.