China is forecast to lead a 48 percent surge in tourist spending in New Zealand by 2021, according to a report released on Monday.

International visitor spending is projected to reach NZ$11.1 billion ($8.25 billion) by that year, up from NZ$7.44 billion last year, according to a report from New Zealand's Ministry of Business, Innovation and Employment.

Visitor arrivals are also expected to increase from 2.85 million last year, growing by 4 percent a year to 3.75 million in 2021.

While Australia was New Zealand's largest visitor market with more than 1.2 million visitors last year, China is expected to outstrip all other traditional markets by 2021, Michael Bird, the ministry's general manager of institutions and system performance, said in a statement.

"Chinese visitors are staying longer and spending more, and we expect this trend to continue.

"Our tourism forecasts predict that China will be New Zealand's largest market in terms of expenditure within the next seven years," said Bird.

The report said 265,000 Chinese visitors went to New Zealand last year and these arrivals will more than double to 571,000 by 2021.

While the average daily spending by Chinese visitors will fall from NZ$309 to NZ$238 over the next seven years, this compares with the average daily spending of all tourists falling from NZ$161 last year to NZ$158 by 2021.

The average length of stay by Chinese visitors is forecast to rise from 18 to 28 days, compared with the overall average rising from 20 to 23 days.

Also on Monday, the Tourism Industry Association forecast that New Zealand's tourism industry will need an extra 36,000 full-time equivalent workers by 2025 in addition to 94,100 in the sector now.