TOKYO, March 20 Reuters The safehaven yen rebounded from early steep declines and the risksensitive Australian and New Zealand dollars flipped to losses as early optimism ebbed over efforts by global authorities to contain a banking crisis.

Japan39;s currency, which is particularly sensitive to longterm Treasury yields, rebounded from losses as steep as 0.6 to last be flat against the dollar as the U.S. 10year yield fell sharply heading into the start of European trading, reversing an earlier 12 basispoint rise.

The Aussie, which at one point had been up by 0.7 to a nearly twoweek top of 0.6743, was last 0.2 lower at 0.6683, sliding back below the closely watched 0.67 mark. New Zealand39;s kiwi was 0.3 lower at 0.6250, giving up an earlier gain of as much as 0.7.

Over the weekend, the Federal Reserve, European Central Bank, Bank of England, Swiss National Bank, Bank of Canada and Bank of Japan announced joint action to enhance market liquidity. That followed Swiss authorities39; negotiation of a buyout of Credit Suisse by UBS, but at a huge discount and with a 17 billion debt writedown.

The market39;s driving force is risk aversion, said Takahiro Sekido, chief Japan strategist at MUFG.

I39;m not so pessimistic, but still we have to wait and see how much we will see risk contagion from Europe, he said. At least within this week, I expect the yen will stay strong.

The yen last traded at 131.79 per dollar , keeping intact a 2.5 gain from last week.

The euro was…