WELLINGTON (REUTERS) - New Zealand Prime Minister Jacinda Ardern on Friday (Oct 2) vowed to tackle the country's chronic housing shortage, focusing in on a vulnerable election issue for the Labour Party ahead of early voting starting this weekend.

Ms Ardern is expected to secure re-election in the Oct 17 poll after winning praise for her handling of the Covid-19 outbreak and other crises, but Labour has done less well on some domestic issues, including plans to build new homes and rein in the cost of housing.

The Labour Party-led coalition's ambitious affordable housing project to build 100,000 homes in a decade has faltered, with only 600 homes being built so far and about a 1,000 under construction.

On Friday, Ms Ardern promised to deliver more homes and replace a 30-year-old law blamed for high housing costs and impeding urban development.

"Overly restrictive planning rules are one of the causes of high house prices," Ms Ardern said, adding she was determined to remove barriers to the supply of land and infrastructure for housing, including replacing the country's Resource Management Act (RMA).

New Zealand's house prices have soared nearly 90 per cent over the past decade, analysts have said, due to a shortage of over 100,000 homes.

Successive governments have failed to ease the red tape around land approval, making land artificially scarce. For private developers the costs and consent process are significant hurdles, making properties unaffordable.

Ms Ardern said the party would also support first home buyers with loans and introduce regulations for property management services.

While opinion polls suggest Ms Ardern is on track for a comfortable win to secure a second three-year term, the opposition National Party has been clawing back support.

National Party leader Judith Collins, whose party said previously it would scrap the RMA, on Friday dismissed Ms Ardern's housing plans as copying its own.

"What Labour's housing announcement is, is an admission of 3 years of failure," Ms Collins said.

Nearly 450 advance polling stations will open their doors on Saturday.

Chief Electoral Officer Alicia Wright said advance voting has become steadily more popular. It accounted for 47 per cent of all votes in 2017 and could reach as much as 60 per cent this time round.

Preliminary results will be announced on Oct 17.