Treasury secretary John Fraser has issued a blunt assessment for the global economy, saying there is "no clear path to growth".

He has also expressed concern about high levels of debt among governments and households, saying it leaves the global economy vulnerable.

In an uncertain economic outlook and continued financial market volatility, it was important both governments and households looked carefully at their debt levels, Mr Fraser told a Senate estimates hearing in Canberra on Wednesday.

"(It) puts them hostage to a situation where if interest rates go up, and I suspect eventually they will ... it makes us vulnerable," he said.

His comments came as global stock markets suffered another rough ride, with Australian shares dropping nearly two per cent at one stage on Wednesday, extending the three per cent tumble of the previous day.

Mr Fraser does not expect such turmoil to disappear, noting this has recently spread to a deterioration in credit markets, especially for bank and energy borrowings.

"The one thing we have learnt in the last 20 years or so is to keep an eye on everything," he said.

On the global economy he said while the US has strengthened, it was a "step too far" to say this would be sustained.

China's outlook was also softer and in Europe the signs were mixed.

"We are swimming against the tide," he said.

The head of the nation's largest retail bank, Commonwealth Bank of Australia, agreed that Australia faced challenges from concerns about the global economy.

"We must be cautious but also remain focused on the long term to ensure Australia remains a great place to live and to invest," Ian Narev said unveiling the bank's record six monthly profit of $4.8 billion profit.

Despite the gloom, new figures showed consumer confidence jumped 4.2 per cent over the past month with the Westpac-Melbourne institute gauge showing optimists outnumbering pessimists.

"While the plunge in the oil price is disturbing from a market perspective, households are now benefiting from lower petrol prices," Westpac chief economist Bill Evans said.

However, he pointed out the latest survey closed prior to this week's renewed slump in share prices.

Retail Council boss Anna McPhee was cautious in being too positive over the latest reading, saying there continues to be an underlying fragility amongst consumers about conditions over the next 12 months.