Activity in Australia's services sector slowed for the fifth consecutive month in September, according to data released on Tuesday.

The Australian Industry Group/Commonwealth Bank Australian Performance of Services Index slid 1.9 points in the month to 45.6. A figure below 50 indicates the industry is contracting.

It was the eighth time this year the index has been below the threshold that separates contraction from expansion, with April the only month having an index above 50.

"September's result indicates a continuation of the weakness that has been seen across the services sector for most of the year," according to AI Group chief executive Heather Ridout.

"A wide variety of factors appear to be contributing to this weakness including tentative consumers and businesses influenced by political uncertainty, volatility in the global economy, the prospect of higher domestic interest rates and the ongoing withdrawal of fiscal stimulus," she said.

"The pressures on businesses across the services sector would intensify if interest rates were to rise when sales are sluggish and employment in the sector is waning."

The survey, which is based on a poll of about 200 companies, was released hours before the RBA rate announcement. It measures sales, new orders, deliveries, inventories and employment for banks, real estate agents, insurers, restaurants, transport firms, retailers and other companies to compile the overall performance of services index.