That was despite an increase in some premiums last year.

Membership grew by 12,756 for the six months ended December 31, compared with total growth for the previous financial year of 7359, chief executive Ian McPherson said.

The increase in new members and lower-than-expected cancallations had brought total membership to 821,125. That was on a combination of concerns about the public health system such as waiting lists and strikes, Southern Cross's emphasis on membership retention, and products offered, McPherson said.

"It seems to be accelerating, although we're not talking about boom times or anything of that sort -- it's good steady incremental growth and we're pretty comfortable with that," McPherson said.

United Future health spokesperson Judy Turner.said the party was keen to see tax concessions for health insurance brought in. Under its policy the breaks would be prioritised with those of 65 benefitting first.

"They are the ones who least can afford health insurance but are too scared to cancel it."

Southern Cross says its low claims reward introduced two years ago may have helped with its growth.

"Our membership gains are telling us that that people are acknowledging the value of health insurance, particularly as the realisation sets in that the public system cannot fund everything for everyone on demand," McPherson said.