A leading economist is warning that employment growth is set to slow during the rest of the year as a measure of job advertisements fell for the first time in four months.

The widely-watched ANZ job advertisements series showed that combined newspaper and internet listings fell by 0.4 per cent last month.

It is the first time job ads have declined since March.

Internet job advertising fell 0.5 per cent in July, seasonally adjusted, while newspaper ads were up 2.2 per cent but now only account for 2 per cent of total job ads.

ANZ chief economist Warren Hogan said the unemployment rate has been surprisingly steady for the last nine months, but other economic indicators suggest it should be rising.

"The improving trend for job advertising, which has been in place now for almost two years, is starting to wane in the last three or four months," he told ABC News.

"So we should expect to see some softer outcomes in the labour market over the second half of 2015."

Warren Hogan observed that even the previously solid growth in employment had not fed through to incomes, and weak wages outcomes were likely to continue.

"Aggregate household income has expanded only modestly as the large number of services jobs being generated are paid significantly less than the jobs lost in the mining and manufacturing industries," he wrote in his note on the data.

"As a result, growth in household spending has remained sluggish."

July's official employment figures are out on Thursday and ANZ is expecting employment to rise by a moderate 15,000, keeping unemployment steady at 6 per cent.

Economists surveyed by Bloomberg are typically forecasting a 10,000-strong jobs gain over July, leading unemployment to edge higher to 6.1 per cent.