Disgruntled homeowners in New Zealand have started a class action lawsuit against government-controlled insurer Southern Response.

The group's lawyer, Grant Cameron, said 47 policyholders had officially filed a case in the High Court at Christchurch on Wednesday over delays by the insurer in settling Canterbury earthquake claims.

He said Southern Response had failed in its duty, with some homeowners still waiting nearly five years after the first of the devastating quakes.

Parties to the action have joined on a "no win, no fee" basis and Mr Cameron said the litigants were waiting on court approval to allow any other interested claimants to join in the next three months.

The legal case was first proposed in March last year following complaints the company was taking too long in settling claims.

At the time, Mr Cameron said homeowners would also be claiming for additional expenses over stress and anguish caused by delays.

But Southern Response blamed continuing aftershocks from the deadly February 22, 2011 earthquake for its delay in starting claims and aimed to resolve 90 per cent of them by 2016.

In July, an individual policyholder won a $NZ300,000 ($A272,800) case against the insurer after the Supreme Court ruled the initial payout for a red-zoned house had been incorrect because of the way it had been calculated.

Southern Response was set up by the government to handle claims for insurer AMI following its near-collapse.

Finance Minister Bill English said legal action over insurance in Christchurch was not uncommon and he expected the company to act in a "sensible, commercial way".

Southern Response said it would issue a comment shortly.