Joe Hockey is hitting back at Labor in the growing fight over tax reform by using official figures to show that police officers and train drivers are using negative gearing more widely than some of the nation’s wealthiest professionals.

In his strongest warning yet against changing the tax breaks, the Treasurer told The Weekend Australian there was “no merit” to amending the rules on negative gearing for residential property.

Australia’s thirst for real estate was confirmed again yesterday when the Reserve Bank revealed that investors spent $6bn on the property market in June, one of the largest monthly figures on record.

Labor’s decision risks antag­on­ising voters who are turning to the property market to build up their wealth, with figures from the Australian Taxation Office showing thousands of ordinary households rely on negative gearing.

As a proportion of workers in various occupations, more police officers use negative gearing than tax accountants and management consultants, according to the ATO statistics analysed by the Treasurer’s advisers.

“Negative gearing is a way for people on medium incomes to get into the property market,” Mr Hockey told The Weekend Australian. “Many hard-working Australians have invested money in real estate … to give themselves some financial security.”