The number of house sales has continued to drop, as prices keep rising.

The number of residential properties sold across New Zealand fell a seasonally adjusted 3.8 percent in June, over last year, according to the Real Estate Institute.

Median house prices across the country rose 4.5 percent in June to $585,000, up from $560,000 the year earlier.

Prices rose over most of the country other than Auckland, Waikato and West Coast, which had flat prices, while Marlborough prices fell slightly by 1.1 percent.

Marlborough was also an outlier when it came to sales. It led the regions with the highest rate of increase in sales - up 18 percent over the year earlier, to the most June sales in three years.

Turnover in the Hawke's Bay and Taranaki fell by about a quarter over last year, although both regions recorded strong price increases of about 10 percent.

"The number of properties sold in New Zealand during June was the lowest for the month of June in five years," institute chief executive Bindi Norwell said, adding that some buyers were finding it difficult to get a mortgage.

"Feedback from parts of the country is that some people are reluctant to list their property for sale without somewhere to move to, and with fewer listings coming on to the market, it's slowing down the property cycle and impacting sales volumes."