* Third decline in five sessions; first weekly drop in four

* Market dropped on weaker rival oils - trader

* Palm to test resistance at 2,578 rgt/T - technicals

(Updates latest prices)

29/08/2016 (Reuters) - Malaysian palm oil futures posted a second straight session of losses on Friday, pulled down by weaker-performing rival oils, and charted a weekly loss following three weeks of gains.

Soybean futures on the Chicago Board of Trade are down on forecasts for above-average crop yields in the United States.

Palm prices are impacted by soy as they compete for a share in the global oilseeds market.

Benchmark palm oil futures for November on the Bursa Malaysia Derivatives Exchange fell 0.4 percent to 2,552 ringgit ($636) per tonne at the close of trade.

Traded volumes stood at 35,543 lots of 25 tonnes each at the end of the trading day, lower than the 2015 average of 44,600.

Palm recorded three sessions of falls this week, reaching a more than one-week low on Tuesday before finding support on strong exports. Palm is 0.7 percent lower this week.

The market is down on weaker soy, a Malaysian trader said.

Another trader from Kuala Lumpur added that the market was also weighed down by lower-performing refined, bleached and deodorised (RBD) palm olien on China's Dalian Commodity Exchange despite stronger Malaysian exports.

Palm oil shipments from Malaysia, the world's second-largest producer after Indonesia, surged 29-31 percent between Aug. 1 and Aug. 25 from a month earlier. The rise stemmed from a surge in shipments to India and stronger Chinese exports, cargo surveyor data showed.

Palm oil seems to have stabilised around support at 2,522 ringgit per tonne and is expected to test resistance at 2,578 ringgit, according to Wang Tao, Reuters market analyst for commodities and energy technicals.

In competing vegetable oils, the Chicago Board of Trade soybean oil December contract rose 0.2 percent, while the January soybean oil contract on the Dalian Commodity Exchange dropped 1 percent.

Palm, soy and crude oil prices at 1043 GMT

Contract Month Last Change Low High Volume

MY PALM OIL SEP6 2798 -4.00 2792 2823 324

MY PALM OIL OCT6 2647 -3.00 2616 2665 1516

MY PALM OIL NOV6 2549 -9.00 2523 2567 17136

CHINA PALM OLEIN JAN7 5474 -68.00 5404 5522 1119344

CHINA SOYOIL JAN7 6280 -60.00 6242 6324 456384

CBOT SOY OIL DEC6 33.39 +1.80 33.15 33.51 7691

INDIA PALM OIL AUG6 564.30 +1.80 559.20 564.9 412

INDIA SOYOIL SEP6 648.7 -1.60 646.5 651 32670

NYMEX CRUDE OCT6 47.22 -0.11 47.01 47.45 54530

Palm oil prices in Malaysian ringgit per tonne
CBOT soy oil in U.S. cents per pound
Dalian soy oil and RBD palm olein in Chinese yuan per tonne
India soy oil in Indian rupee per 10 kg
Crude in U.S. dollars per barrel

($1 = 4.0130 ringgit)
($1 = 67.0400 Indian rupees)
($1 = 6.6688 Chinese yuan)