The Australian currency opened nearly two US cents stronger, bolstered by positive investor sentiment following comments from the central bank and the US Federal Reserve earlier in the week.

At 7am AEST, the local unit was trading at $US0.8936/40, well above yesterday's end of $US0.8767/69

The Aussie ranged from $US0.8952 to $US0.8748 since 5pm AEST on Thursday.

"It's been very strong overnight and interestingly has outperformed everything," said Commonwealth Bank vice-president of institutional banking and markets Tim Kelleher.

"Part of the rise is a little bit of the Reserve Bank (RBA) minutes and governor Glenn Stevens' speech from Tuesday.

"To explain the Aussie out-performance, you have to talk about US Fed chair Ben Bernanke's speech and the performance of the Aussie economy."

Mr Bernanke, on Wednesday night, told a congressional committee the outlook for the US economy was "unusually uncertain".

This saw investors abandon the greenback and left the US bourse in the red both on Wednesday and Thursday night (AEST).

Contrary to Mr Bernanke's remarks, the RBA's comments on Tuesday showed the central bank expects growth ahead for the Australian economy.

However, the minutes of RBA's July 6 board meeting, also hinted strongly that a sharp rise in official inflation figures due next Wednesday could push the central bank to increase the benchmark rate on August 3.

That could take the cash rate up from 4.5 per cent to 4.75 per cent in the middle of the federal election campaign.

Mr Stevens emphasised RBA will continue to make adjustments based on economic data regardless if an election is under way.

"The board will meet (on August 3). It will consider all the issues for the economy and do its job," Mr Stevens told an Anika Foundation Luncheon in Sydney on Tuesday.

Also propping the Australian dollar in offshore trade were strong commodity prices and a return to risk on the US share market, which closed Thursday's trade higher.

According to Mr Kelleher, today's local session offered potential to the Australian currency to trade stronger, possibly pushing up to $US0.9000.

"But there are a lot of headwinds up to 90 US cents."

The domestic unit would have downside support at about $US0.8950, he said.