Australian Gas Networks gives these instructions: ‘If you smell gas in the street or on your property before or including the meter, you should call your state Gas Leaks and Emergency Number (VIC/NSW: 1800 GAS LEAK/1800 427 532) to locate and repair the leak. If however, you believe the leak to be after the meter on a section of pipe work connecting your appliances, or on the appliance itself, you should contact a licensed natural gas fitter to rectify the problem.
for detailed natural gas emergency procedures.