New Zealand has slipped again, to fourth, in the latest anti-corruption global rankings.
Transparency International, which released its latest rankings this afternoon, warned this country would fall further if its public access to information and environmental protections did not keep pace with northern Europe's.
New Zealand had topped the Corruption Perceptions Index of 168 countries as recently as 2013 and 2012, and seven times in total.
But Denmark, Finland and Sweden had overtaken it, and were now perceivedto have the least corrupt public sectors.
A falling ranking could put companies off doing business here and act as a turn-off for tourists and qualified migrants, Transparency International New Zealand chair Suzanne Snively said.
"Our government must act immediately to re-establish New Zealand's stand-out reputation for a trusted public sector," she said.
Countries are scored highly for press freedom, public access to information about government spending and fair judges, among other things.
New Zealand scored 88 points out of 100, compared with Australia, which was on 79 and fell from 11th to 13th in the 2015 rankings.
North Korea and Somalia each scored just eight points and came last.