* Safe havens yen, Swiss franc bid as tensions in Ukraine heighten
* Participants also focused on U.S. data this week
* Euro holds up as ECB easing expectations fade
By Ian Chua and Shinichi Saoshiro
SYDNEY/TOKYO, March 3 (Reuters) - The Japanese yen gained broadly on Monday while investors sold risk currencies such as the Australian dollar after Ukraine's mobilisation to counter possible Russian invasion heightened geopolitical risks.
The U.S. also threatened to isolate Russia economically in Moscow's biggest confrontation with the West since the Cold War.
The euro fell as low as 139.36 to the safe-haven yen, from 140.56 late in New York on Friday.
Both the U.S. dollar and the Australian dollar dipped to one-month lows of 101.25 yen and 90.08 yen respectively, with the slide in Tokyo shares adding an extra boost to the Japanese currency.
The safe-haven Swiss franc was also in favour, rising to its highest in over a year against the euro. It rose as far as 1.2108 francs per euro before edging back to 1.2116.
Investors were wary of testing the Swiss National Bank's commitment to defend its cap of 1.20 per euro on the franc.
Dealing risk appetite a further blow, a government survey on Saturday showed activity in China's factory sector slowed to an 8-month low in February, reinforcing signs of a modest slowdown in the world's second biggest economy.
Participants kept one eye on tension between the two former Soviet republics and the other on more fundamental factors with potential impact on currencies.
"Geopolitical risks will keep the dollar under pressure for now, but we do have the U.S. employment data on Friday and focus is likely to shift back to fundamentals towards the end of the week," said Shin Kadota, chief Japan FX strategist at Barclays.
A run of data, including the ISM manufacturing report on Monday, the ISM non-manufacturing report on Wednesday and factory orders on Thursday will give investors an opportunity to gauge the U.S. economy's health and its potential implications for the Federal Reserve's plan to unwind its stimulus programme.
The euro last traded at $1.3778 some 0.2 percent lower compared with late New York levels.
The euro hovered within distance of a two-month peak above $1.3820 touched on Friday after data showed inflation was steady in the euro zone and cooled expectations the European Central Bank might ease monetary policy later this week.
"The Ukrainian situation is not resulting in strong selling of the euro so far, but the single currency may still come under negative pressure from expectations surrounding ECB monetary policy," said Kadota at Barclays.
Analysts at JPMorgan described two scenarios that could unfold from the Ukraine crisis: a possible repeat of the January 2009 interruption of natural gas supplies from Russia to Europe via Ukraine, and the less-likely possibility of military conflict next door to the EU.
They said markets discounting the risk of a gas supply disruption would mark down euro against the U.S. dollar. Europe imports around 25 percent of its gas from Russia, although there are huge variations across countries, JPMorgan said.
"But unless that interruption is sustained for many weeks, Ukraine does not look like a trend driver of government bonds, swap spreads or the currency," they said.
However, should the extraordinary event of military conflict occur, they warned the euro could drop 3 to 5 U.S. cents.
Against the greenback, the Aussie is down about 0.3 percent at 89 U.S. cents.