The BNZ-Business New Zealand performance of services index for March gained 5.5 points from February to reach 58.3 in March - its highest level of activity since November 2007.
Scores above 50 reflect expansion, and below 50, contraction.
Otago-Southland's services rating mirrored its result within last week's separate manufacturing index, where the southern regions had been making a strong show in recent months, albeit plagued by the New Zealand dollar's strength.
BNZ economist Doug Steel said it ''no surprise'' to see widespread service sector gains, given that expansion in general was not only deepening but widening. Growth was being experienced across several sectors, including construction, agriculture, manufacturing, tourism and retail.
The index includes tourism and hospitality and services to business and the health sectors.
The North Island's northern region rose 1.7 points to 59.4, following three consecutive months at the 57-point mark.
The North Island's central region dipped 0.5 points to 59.2 from February, but was still at a ''very healthy'' level of activity, while in the South Island, the Canterbury-Westland region recovered from a dip a month earlier and posted 58.5 for March, Mr Steel said.
