The Australian dollar reached a post-float high for the third straight day after the US central bank indicated it would not raise interest rates in the near future.
On Thursday, the Australian unit reached 109.47 US cents, its highest level since the currency was floated in December 1983. Its low since 0700 AEST on Thursday was 108.52 US cents.
At 1700 AEST, the local unit was trading at 109.12 US cents, up from 108.20 cents on Wednesday.
The US central bank's Federal Open Market Committee (FOMC) ended a two-day meeting early on Thursday (AEST), with chairman Ben Bernanke saying the bank would complete its $US600 billion ($A556.2 billion) economic stimulus plan in June as planned.
Royal Bank of Scotland foreign exchange strategist Greg Gibbs said the Australian dollar continued its climb after Dr Bernanke's comments. "We're seeing weakness in the dollar following Bernanke's speech overnight," Mr Gibbs said.
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"That's followed through to the session today with a number of big moves in the Asian currencies, the euro and the Aussie," he said.
"Another key factor is the strength in the CPI (consumer price index) yesterday and the risk that creates for local policy."
On Wednesday, the Australian Bureau of Statistics (ABS) said the CPI rose in the March quarter by 1.6 per cent for an annual inflation rate of 3.3 per cent, above market expectations.
That increased speculation that the Reserve Bank of Australia will raise its interest rate sooner than previously expected.
The interest rate gap between Australia and the US is currently as much as 4.75 percentage points, and that may widen further if there are rate rises in Australia, making the local currency more attractive.
Australia's current cash rate is 4.75 per cent, while the US rate is set in a range of zero to 0.25 per cent.
On Thursday night, the market is expected to focus on March quarter US economic growth data, which is expected to show GDP grew by 1.8 per cent over the first three months of the year.
The Reserve Bank of Australia's trade weighted index (TWI) was at 79.1, the highest since 1985, up from 78.7 on Wednesday.
