* Euro near 5-week low vs dollar on Ireland debt problems
* Technical analysts looking for daily close under $1.3690
* G20 meeting under way, market sets expectations low
(Adds detail, updates prices, adds comment)
By Steven C. Johnson
NEW YORK, Nov 11 (Reuters) - Doubt about Ireland's ability to repay its debts spread on Thursday, driving the euro lower and overshadowing G20 attempts to ease currency tensions and secure commitment to more balanced global growth.
Yields on 10-year Irish bonds rose well above 8 percent to a record high over comparable German debt. Investors worried the country wouldn't be able to cut spending as planned and may require a bailout, with bond holders forced to absorb losses.
The euro fell as low as $1.3642, a five-week trough, and was last down 1 percent at $1.3656. It also fell against the yen and hit a seven-week low against sterling.
"The euro can't sustain even modest upticks right now," said Marc Chandler, global head of currency strategy at Brown Brothers Harriman, adding that its break of $1.3650 "could open up another two-cent decline."
He added, "Europe never fully addressed these problems, and it's clear solvency issues in Ireland have not been resolved."
Some traders said solvency fears were spreading, with a rise in Spanish bond yields increasing market anxiety.
"If Spain is coming under the microscope, we could have a larger breakdown in the euro given the size of the Spanish economy," said Brian Dolan, chief strategist at Forex.com in Bedminster, New Jersey.
Dolan said $1.3520 may emerge as the next target, while other traders said demand for downside options, particularly one-month $1.3200 strikes, would keep pressure on the euro.
INCREASED DOLLAR APPEAL
The spike in Irish yields and decline in German ones as investors seek shelter in bunds has happened as U.S. yields have turned higher, lifted partly by a string of strong U.S. economic data, including last month's employment report.
That makes holding the dollar more attractive and also helped it rise above 82 yen this week for the first time since early October. It was last up 0.2 percent at 82.52 yen.
There was still uncertainty about the dollar's medium-term outlook, especially after the Federal Reserve said it would buy some $105 billion in Treasuries over the next 30 days.
The Fed said it would buy $600 billion of Treasuries by mid-2011 to lower U.S. interest rates and boost slow growth, though a U.S. think tank report on Thursday the central bank could buy fewer bonds if the economy improves.
Trading was lighter than usual, with some markets in the United States and Canada closed for holidays.
G20 MEETS IN SOUTH KOREA
Europe's woes diverted attention from a G20 summit in South Korea. Discussion was expected to include exchange rate policies and global economic imbalances, though few investors expect a sweeping agreement.
Much of the disagreement on currencies lies with the United States and China, with the former eager to see the Chinese yuan appreciate at a faster pace.
A senior Chinese central bank official said China had no intention to confront the U.S. over its currency rate, and that the issue should not be politicized.
China has criticized the Fed's policy, saying it is stoking inflation beyond U.S. borders, and former Fed Chairman Alan Greenspan said Wednesday the U.S. central bank was pursuing a weaker dollar policy, prompting a swift denial from Treasury Secretary Timothy Geithner.
(Additional reporting by Neal Armstrong in London; Editing by James Dalgleish and Andrew Hay)