BUENOS AIRES, May 28 (Reuters) - Argentina's stock, currency and bond market trends on Friday:

* The MerVal stocks index gained as rising global oil prices boosted energy-related shares. The index rose 1.71 percent to close at 1,587.21 points.

* Index heavyweight Tenaris (TENA.BA: Quote, Profile, Research), the world's leading producer of seamless steel tubes for the energy industry, rose 3.53 percent to 60.15 pesos.

* Oil rose to a six-month high above $66 per barrel on Friday, making largest monthly percentage gain in more than a decade after U.S., Japanese and Indian data suggested the economic downturn may be easing.

* On the broad stock market in Buenos Aires, volume was moderate at $22.4 million.

* Prices for government bonds traded over-the-counter in Buenos Aires fell on average 0.6 percent as investors pocketed profits from recent gains.

* The peso-denominated Disc bond ARDISCD=RASL shed 3.3 percent and the dollar-denominated Boden 2012 ARBODEN12D=RASL fell 2.7 percent, according to the ask price.

* In formal exchange between banks, the Argentine peso fell 0.13 percent to end at 3.7475/3.75 per dollar ARS=RASL.

* In informal trade between foreign exchange houses, as measured by Reuters, the peso weakened 0.26 percent to 3.8075/3.8125 ARSB=. (Reporting by Walter Bianchi and Jorge Otaola; Writing by Kevin Gray; Editing by Diane Craft)