* Investors trim short dollar positions but weakness intact
* Euro slips vs dollar, earlier climb loses momentum
* Dlr/yen slides near pre-intervention levels, BOJ awaited
(Adds comment, updates throughout)
By Naomi Tajitsu
LONDON, Oct 4 (Reuters) - The dollar rose on Monday, recovering earlier losses as traders cut bets the currency will weaken, which have been piling up on speculation the Federal Reserve may further ease U.S. monetary easing.
The euro slipped, retreating against the dollar as upward momentum in the single European currency petered out just above a 6 1/2-month high, prompting investors to trim long positions.
Against the yen, the dollar hovered near a 15-year low, fuelling speculation Japan may re-enter the market to stem strength in its currency.
This week sees the release of crucial U.S. jobs data while the central banks of Australia, the euro zone, Japan and the United States hold policy meetings. The International Monetary Fund and Group of Seven finance ministers also meet this week.
Given these risks, analysts said investors were likely to trim some of their short dollar positions even though many in the market expect the prospect of more U.S. quantitative easing will continue to hurt the currency.
"The market has a substantial short dollar position and when you're going into a big data week, you wonder whether the positioning risk is worth it at this juncture," said Paul Mackel, director of currency strategy at HSBC.
"We could see a mild reversal of short positions until the market drips through the data on Friday, but I don't think the trend will change. It's still sell the dollar on rallies, but it just feels the trade (to sell dollars) is getting crowded."
Currency speculators' bets against the dollar swelled to $22 billion in the week to Sept. 28, the highest since at least mid- 2008, Commodity Futures Trading Commission data showed. [IMM/FX]
The euro EUR= slipped 0.7 percent to $1.3685 after earlier poking above $1.3800 for the first time since mid-March. Analysts said its rally lost momentum above that level, leading to short-covering in the dollar.
The euro was unable to hold earlier gains made after China pledged on Sunday to support a stable euro and not to reduce its holdings of European government bonds. [ID:nLDE69204K]
"The fact that the euro didn't go up more on that news suggests it's looking a bit tired," HSBC's Mackel said.
Traders in London said Asian demand to sell euros was helping to push it lower, as was an early slide in European shares .FTEU3 and M&A-related demand to sell the currency.
This helped push the dollar up against a currency basket. The dollar index .DXY rose 0.5 percent to 78.464, pulling back from 78.029 hit on Friday, its weakest since January.
Analysts said markets may turn volatile before Friday's U.S. non-farm payrolls data. Signs the labour market continues to suffer may ratchet up speculation the Fed will launch more QE and add to dollar weakness, they said.
Despite Monday's gains, analysts said thre dollar's downward trend would remain intact, particularly versus the euro.
"General dollar weakness can play out versus the euro, but not against the yen," said Ulrich Leuchtmann, currency analyst at Commerzbank in Frankfurt."As long as there's general dollar weakness and it trades so close to 83.00 yen, there's always the chance that Japan will step in."
The dollar JPY= traded at 83.20 yen, little changed on the day but retreating from 83.88 yen hit in Asian time. Traders said stop-loss orders were suspected under 83.00 yen.
The Bank of Japan began on Monday a two-day policy meeting and was expected to extend a cheap fund-supply tool to help shore up the struggling economy. [ID:nTOE69003G]
Some market participants said there was speculation any BOJ stimulus steps may be followed by more yen-selling intervention. Some analysts expect Japanese authorities to step in to sell yen if the dollar falls under 83 yen, as they did last month.