SINGAPORE, Aug 1 Reuters The yen slipped to a fresh threeweek low on Tuesday as the Bank of Japan39;s steps last week to tweak its yield curve control policy weighed on the currency, while the Australian dollar fell after the Reserve Bank of Australia left cash rates unchanged.

Australia39;s central bank on Tuesday held interest rates at 4.1 for a second month, saying past increases were working to cool demand, but warned some more tightening might be needed to curb inflation.

The Australian dollar fell 0.73 to 0.6668 after the decision, nearly wiping out its 0.87 gains it clocked in July.

Matt Simpson, senior analyst at City Index, said the Aussie move suggested not everyone was positioned for RBA39;s hold, noting that weakerthanexpected data from China also weighed on the risksensitive currency.

I think it was right that the RBA held today, given trimmed mean inflation and unemployment matched the RBAs forecasts. And it may have sent a confusing message had the hiked following softer inflation and retail trade data.

Earlier in the session, the yen slipped to 142.84 per dollar, its lowest in three weeks. It last fetched 142.79, down 0.36.

The Asian currency has been on a wild ride since Friday, when the BOJ took another step toward a slow shift away from decades of massive monetary stimulus, saying it would offer to buy 10year Japanese government bonds at 1.0 in fixedrate operations, instead of the previous rate of 0.5.

Markets could test just how…