* Euro under broad selling pressure, Greece jitters remain
* China tightens policy, high-risk currencies tumble
* EU pledge to help Greece short on details, analysts say
(Adds comments, updates throughout)
By Naomi Tajitsu
LONDON, Feb 12 (Reuters) - The euro hit an 8 1/2-month low against the dollar on Friday after a European Union summit on Greece failed to quell uncertainty about Athens's debts, while monetary tightening by China pushed high-risk currencies lower.
Beijing's move to raise its banks' reserve requirements fuelled risk aversion on the view it may choke its economic recovery. The move pushed the dollar index to a seven-month high while the high-yielding Australian dollar tumbled broadly.
EU nations on Thursday offered their solidarity and support to help Athens rein in its deficits, but the lack of details on how to help kept investors jittery, resulting in widening yield spreads between benchmark government bonds in Greece and Germany -- widely considered the safest in the euro zone.
Concern over how Athens will service its debt has fuelled risk aversion and hammered the euro -- it has fallen nearly 10 percent since late 2009 -- and analysts said China's surprise announcement only aggravated selling in high-risk currencies.
"It's very difficult to see a silver lining for the euro at the moment as it's very difficult to see a solution for Greece," said Jane Foley, currency research director at Forex.com in London.
"And certainly, with China slowing too, it just enhances the safe-haven behaviour towards the dollar."
The euro <EUR=> fell roughly a full percent on the day to $1.3538, according to Reuters data, its weakest since May 2009. The euro's losses pushed the dollar to 80.729 against a currency basket, its highest since July 2009. Sold across the board, the single European currency struck a decade low against the higher-yielding Australian dollar <EURAUD=R> at A$1.5275 and its weakest versus the Canadian dollar <EURCAD=R> since late 2007.
It plumbed its lowest against the Swedish and Norwegian crowns since autumn 2008.
"The EU's intentions are good, but the market would like details," said Kasper Kirkegaard, currency analyst at Danske in Copenhagen, referring to the EU's pledge to support Greece.
"Until we get more details on a political solution for Greece, the euro is going to stay under selling pressure."
Other analysts said that deep, structural cracks in the euro zone exposed by Greece's woes would keep the euro weak.
Adding to the pain were figures on Friday showing the euro zone's gross domestic product rose only 0.1 percent in the fourth quarter, suggesting its economic recovery has lost steam as German growth stalled in October-December. [ID:nLDE61B11U]
The Australian dollar fell roughly 1.4 percent against its safe-haven U.S. counterpart <AUD=D4> to a day's low of $0.8786 after China surprised markets with a 50 basis point increase in banks' reserve requirements. [ID:nTOE61B069]
The move, which can slow bank lending, dampen rising inflation and may slow Beijing's economic growth, pushed the Australian currency down 1 percent versus the yen <AUDJPY=R> to 78.86 yen.
The view that China's tightening may slow growth on a global scale and reduce demand for natural resources hit the commodity-linked Australian dollar, which often appreciates on speculation for economic strength.
The next step in the Greek crisis are meetings early next week of EU finance ministers, although analysts said that might still be too early to expect much clarity on what the bloc will do to help Athens tackle its debt. [ID:nLDE61A0W2] (Editing by Patrick Graham)