New Zealand universities have tumbled out of the top ranks in the latest world rankings by subject.

The latest rankings by the London-based agency Quacquarelli Symonds (QS) have downgraded 74 out of the 166 departments which it ranks across New Zealand's eight universities.

The University of Auckland, which still has the country's largest number of departments rated in the world's top 50, with 13 top-50 subjects, has dropped out of the top 20 in all subjects for the first time.

Its archaeology department, which was ranked 10th last year, has plunged to 23rd, and its education department has slipped from 17th in the world to 26th.

The University of Otago is now the country's only university with a top-20 department - sports-related subjects, which just scraped in at 20th in the world.

Overall, 68 of the 166 NZ departments ranked were rated in the top 100 for their subjects, down from 74 last year.

Based on the number of top-50 departments, New Zealand's university system as a whole slipped from 14th place last year to 18th.

Universities New Zealand chief executive Chris Whelan has blamed inadequate funding for the decline.

He told Mike Hosking Australian universities receive around 27 percent more funding per student than universities here.

He says those in the UK receive 73 per cent more funding than New Zealand, and in the US that figure rises to 97 per cent.

"The fact is that we're increasingly poorly funded compared to the countries we compare ourselves against."

He says funding is not keeping up with the rising cost of running universities.

"There's only so much belt-tightening you can do, and if this country wants a university system where it doesn't matter which university you go to, you get a university education, you need to invest in that."

Whelan says there's massive global competition for the rankings, and New Zealand needs to up their game.

"It's the way you attract international students, it's the way you attract the best academic staff to do the best research and the best teaching."

If we don't improve, he warns we might risk seeing a decline in international students.

QS research director Ben Sowter said NZ universities slipped behind on "employability" - a ranking based on a survey of 42,000 employers worldwide on how they regard graduates from each university department.

"Though the number of NZ university departments achieving top scores for research has increased slightly year-on-year, the number achieving top scores for our employability indicator has slightly decreased," he said.

Number of top-50 subjects

University of Auckland: 13

University of Otago: 2

Massey University: 2

Victoria University of Wellington: 2

Auckland University of Technology (AUT): 1

Waikato University: 0

University of Canterbury: 0

Lincoln University: 0