* Brent, WTI prices drop about 1 percent
* U.S. rig count gains for 13th consecutive week
* Market braces for uncertainty after failed N.Korea missile test (Adds comment)
By Aaron Sheldrick
TOKYO, April 17 (Reuters) - Crude oil fell on Monday in quiet trading after the three-day Easter break on signs the United States is continuing to add output, undermining OPEC efforts to support prices, and as the market digested North Korea's failed missile launch on Sunday.
Benchmark Brent crude futures LCOc1 were down 56 cents at $55.33 at 0618 GMT. On Thursday, before major markets closed for the holiday break, they settled up 3 cents at $55.89 a barrel.
U.S. West Texas Intermediate (WTI) crude futures CLc1 were down 51 cents at $52.67 a barrel, after rising 7 cents to $53.18 on Thursday.
Both benchmarks last week rose for a third consecutive week, with Brent adding 1.2 percent over the four days before the Good Friday holiday and WTI up 1.8 percent.
Trading was subdued to start the week with major market centre London still closed for the Easter holidays on Monday.
While markets are braced for the possibility of more geopolitical tensions over North Korea, the attempted launch on Sunday of a ballistic missile fizzled as the projectile blew up almost immediately. drop in tensions following North Korea's failed missile test ... have seen oil fade in Asia," said Jeffrey Halley, senior market analyst at futures brokerage OANDA in Singapore.
"The soft U.S. CPI (consumer price index) on Friday will ease yields further, also undermining the reflationist markets such as oil and precious metals," he said. sales in the U.S. fell for a second straight month in March and consumer prices dropped for the first time in just over a year, official data showed on Friday.
In the oil patch, U.S. drillers last week added rigs for a 13th straight week, a sign output gains there will continue.
Energy services firm Baker Hughes said on Thursday drillers added 11 oil rigs in the week to April 13, bringing the count up to 683, highest in about two years. RIG/U
Increasing U.S. output is proving a constant source of irritation to attempts by the Organization of the Petroleum Exporting Countries (OPEC) and other major oil producers to curb output and sustain a rally in prices in a market that has been oversupplied since mid-2014.
U.S. crude oil production has climbed to 9.24 million barrels per day, according to the latest Energy Information Administration data, making it the world's third-largest producer after Russia and Saudi Arabia.
While compliance has been strong among OPEC countries, production cuts have lagged among others that have agreed to act to curb oil prices, including Russia. That may be about to change, said BMI Research.
"Non-OPEC compliance will improve over the next two months with Russia driving the largest reductions in volume terms," BMI said. "Kazakhstan is likely to continue to exceed its quota given strong output from the Kashagan field."
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http://tmsnrt.rs/2prZqNl CHART: Brent oil may retest resistance at $56.33
http://tmsnrt.rs/2prvJw4
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