Portal Resources Ltd.
TSX VENTURE : PDO

Portal Resources Ltd.

July 20, 2005 11:30 ET

Portal Cuts Additional Gold/Silver Veins at Arroyo Verde

VANCOUVER, BRITISH COLUMBIA--(CCNMatthews - July 20, 2005) - Portal Resources Ltd. (TSX VENTURE:PDO) is pleased to report on the ongoing drill program at the Arroyo Verde Gold/Silver Project in Chubut Province, Patagonia, Argentina. A total of 11 holes have been completed in the Arroyo Verde Main Dome area, six on the Principal Vein, four on the Northwest Vein area, and one on the large covered southern part of the Main Dome, 500 meters to the south of the Principal Vein. Drilling will resume on July 20, 2005 after a 14 day break for the drilling crews.

Results of the first six holes on the Principal Vein having been previously reported with significant intersections in five of the six holes drilled to date. Values ranged from 4.28 g/t gold equivalent over 0.80 meters in hole PO40 up to 80.25 g/t gold equivalent over 2 meters in hole PO39 (Portal News Release 05-12 dated July 5, 2005).

Four holes have also tested the North West Vein area with assay results pending. All drill holes have intersected narrow multiphase quartz veins 0.40 - 0.75 meters in width with disseminated sulphides similar to previous high grade surface samples and drill intersections. Several of the veins have wide quartz-sulphide crackle breccia zones in the hanging walls of the vein intersections. Assays will be reported when received.

One hole has been completed within the large Arroyo Verde Dome geophysical anomaly located 500 meters to the south of the Principal Vein within the gravel covered southern part of the Dome. This anomaly, measuring 2,000 meters long by 1,000 meters wide, consists of coincident chargeability and resistivity. The first hole drilled to a 200 meter depth, intersected highly altered rhyolite and metamorphic rock beneath 37 meters of gravel cover. A zone of quartz veining, up to 80 percent, in silicified metamorphics was intersected from 135 to 145 meters with a massive quartz vein from 145 to 146 meters then veining up to 50 percent from 146 meters to 158 meters (true width is approximately 70% of the apparent width). Disseminated sulphides, predominantly pyrite and galena are observed through out the quartz vein and zones of veining. Assay results of the vein intersections will be reported when received.

"We are very encouraged by the new vein area discovered in the South Dome as it greatly expands the potential of the Arroyo Verde Project. Undoubtedly more will be found as we explore these large geophysical anomalies for the first time. Drilling continues." stated David Hottman, Chairman

Samples for analysis are collected from the site by Alex Stewart Argentina S.A., a subsidiary of the international laboratory Alex Stewart (Assayers) Limited and transported to their laboratory in Mendoza. Samples are analyzed by fire assay for gold and silver. All work on the project is under the direction of Mr. Gary Nordin P.Geo. British Columbia, the designated Qualified Person for the Arroyo Verde project in accordance with National Instrument 43-101.

ON BEHALF OF PORTAL RESOURCES LTD.

Bruce Winfield, President & CEO

The TSX Venture Exchange does not accept responsibility for the adequacy or accuracy of this release.

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