The national index reading was 55.6 points in September, up 2.3 points from August and consistent with the ''healthy levels'' of expansion seen this year, BusinessNZ chief executive Phil O'Reilly said yesterday.
Otago-Southland led the regional indices on 58.2 points, well up from the 48.5 recorded in September last year and 34.4 recorded in September 2011.
Mr O'Reilly said the ''significant improvement'' from Otago-Southland was mainly because of a strong increase in new orders and business.
Northern was the second-highest region with 57.3 points, followed by Canterbury on 55.6, the same as the national average, and Central on 51.9.
''Overall, there are a number of factors to show the sector continues on the right path. The proportion of positive comments remains healthy at almost 64% in September, while new orders and business also remains strong.
''With the same nine months in 2011 and 2012 average 52.5 and 53.6 respectively, the 2013 average clearly shows the economy picking up pace.''
BNZ economist Doug Steel said the September index results were more important than they looked. A series of softer spots appearing in August had gone, keeping intact the firmly positive underlying growth trends seen in the service sector in the past year.
The service sector includes lawyers, accountants, financial services, the hospitality sector and tourism.
