The Reserve Bank of Australia could be forced into unconventional policy measures such as money printing to save the economy from stagnation if its latest round of interest rates cuts fail to stimulate growth, economists have warned.

After cutting the cash rate for the third time this year on Tuesday to a fresh record low of 0.75%, the central bank warned that there could be more cuts to come as it pursues its twin targets of reducing unemployment and keeping inflation between 2% and 3%.

But it has failed to meet the inflation aim for 20 successive quarters, leading to increasing speculation that it will be forced to use less conventional methods such as buying up billions of dollars of government bonds to flood the financial system with money.

This controversial process, known as quantitative easing (QE), was used after the global financial crisis by central banks in the US, UK, eurozone and Japan. In the latter two cases, inflation still remains extremely low.

The investment bank heavyweight Goldman Sachs said on Wednesday that the RBA could resort to a $200bn bond-buying scheme if, as many economists expect, its rate cuts don’t lift inflation.

Andrew Boak, Goldman Sachs’ chief economist in Australia and New Zealand, said in a research note that negative interest rates would be needed to boost inflation to the target level and therefore estimated “an equivalent degree of stimulus could be approximated by a $200bn QE program”.

He added: “We continue to see a material risk that the RBA will deliver even deeper rate cuts and be drawn into unconventional policies.

“For now, however, this remains outside our central scenario given governor Lowe’s concerns about financial stability risks from loose monetary policy.”

Most economic forecasters believe another rate cut is only a matter of time after RBA governor Philip Lowe emphasised more headwinds on jobs and wages growth in his statement after Tuesday’s meeting.

UBS economists, who were among the first to predict that the bank would cut the cash rate this year, now forecast the bank will go to 0.5% in November after Lowe’s surprisingly comments.

Westpac economists also believe that with the cash rate almost certainly headed to 0.5%, “we need some unconventional monetary policy boost” such as bond buying to meet the bank’s target.

“When you get to 0.5% you have to bring in other measures,” said Damien McColough, Westpac’s head of rates strategy.

Another factor pushing rates lower – and raising the prospect of QE – was the likelihood that other central banks would continue to cut their own borrowing costs. The US Federal Reserve is expected to reduce borrowing costs again this month, which puts pressure on others to follow suit. The European Central Bank, meanwhile, has pledged to restart its massive bond-buying program and the Bank of England said it would likely cut rates even if Brexit does not go ahead.

Such moves would force smaller central banks like the RBA to keep rates low or risk a higher currency.