Demand for Canterbury rental properties has sharply increased since the magnitude 7.1 earthquake, say several real estate companies.

Inquiries had increased "quite dramatically" and there would be an "imminent shortage" in rentals within a week, Tony McPherson, of Christchurch's McPherson Property Management said.

About 3000 Christchurch homes were currently uninhabitable, due to the September 4 quake, resulting in people wanting rentals straight away, he told NZPA.

Most of the company's available rental properties were two-bedroom flats but many people wanted bigger homes suitable for families: "I can see we will get to a stage where people will have to compromise," he said.

An influx of workers into the city to help with the recovery was also behind the hike in demand.

"We've had a lot of inquiries, especially for furnished accommodation, from companies sending people into Christchurch," he said.

However he wasn't increasing rents at this stage.

"At the end of the day the market place will determine rental values but there's no ramping or anything going on," he said.

A director of a Riccarton real estate company, Whittle Knight and Boatwood Ltd, had also noticed far more inquiries.

"We're getting steady inquiries from people saying `yeah we've been condemned and we've got to get out and we want somewhere to go'," said Gill Knight.

The agency could meet the current demand but things would get more difficult as inquiries built up, he said.

Stressed families wanted to move into rentals immediately, which the agency was doing its best to accommodate. It did not plan to put up the rent of its advertised properties post-quake.

"We set our figures...We're not cranking the rents up because of the occasion," he said.

Department of Building and Housing's Jeff Montgomery said Christchurch's rental market was coming under pressure.

"We've had feedback from property managers in Christchurch that properties are moving off their books quite quickly," he said.

He was not aware of rental agencies putting prices up for advertised properties.

"It's entirely up to the landlord to make a decision about what market rent they think they can get for their property. There's no rules around it," he said.

The department provided statistics on its website, which suggested appropriate market rates per suburb.

Mr Montgomery said landlords must give tenants 60 days notice if they wanted to increase rent.