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Vancouver, British Columbia: Calibre Mining Corp. (TSX-V: CXB) (the "Company" or "Calibre") announces preliminary exploration results from the Primavera prospect in the Borosi Concession of Northeast Nicaragua. The Primavera property is subject to an option agreement with B2Gold and is 7 kilometres south of the historic Santa Rita copper-gold skarn mine.

The Primavera prospect covers a 5 kilometre by 7 kilometre area dominated by Tertiary volcanics in which Calibre's exploration team has mapped quartz veins, diorite intrusives, and calcareous sediments. The prospect area is associated with coincident gravity, magnetic and radiometric high signatures identified from an airborne geophysical survey, believed to represent a large intrusive centre. The area is thought to be prospective for intrusive related skarn, epithermal and porphyry mineralized systems.

During the initial exploration program, Calibre collected over 250 rock samples and completed over 52 line-kilometres of soil sampling. Reconnaissance sampling in 2010 identified high grade gold and copper mineralization of 31.8 g/t Au and 2.41% Cu (sample B10R1372), 24.8 g/t Au and 0.14% Cu (sample B10R4083), 14.65 g/t Au and 1.33% Cu (sample B10R1371) and 34.1 g/t Au (sample B10R5092) from quartz veins and breccias hosted by volcanic andesites in the central part of the prospect area. Follow up soil grids have identified three additional areas of substantial gold and copper anomalies. This work is highlighted by results from the northern most soil survey grid that identified an 850 metre by 300 metre area with a coincident gold-copper soil anomaly containing values consistently over 100 ppb gold (up to 1.18 g/t Au) and 250 ppm copper. The anomalous soils are associated with an area coincident with a magnetic low and where quartz stockwork veining has been found in andesite volcanic float. The anomalous area remains open to the west and north. Soil survey data and updated maps are available at www.calibremining.com.

"We are extremely pleased with the initial exploration results from Primavera and believe that we have identified an intrusive related mineralized system that warrants substantial further exploration." stated Robert Brown, President and Chief Executive Officer of Calibre "We are very excited about the exploration potential of our Borosi concessions. Not only have we had success in outlining a new discovery at Primavera, but Calibre recently tabled an NI 43-101 inferred resources of 835,450 ounces of gold and 4.28 million ounces of silver from our 100% owned Cerro Aeropuerto and La Luna projects (see news release 04/13/2011) and we continue to intercept high grade gold and silver mineralization at our 100% owned Riscos de Oro property (see news release 04/15/2011)."

Quality assurance and quality control procedures include the systematic insertion of blanks, standards and duplicates into the soil and rock sample strings. Samples are placed in sealed bags and shipped directly to ALS CHEMEX labs in North Vancouver, BC for gold fire assay and ICP multi-element analyses. The technical content in this news release was read and approved by Roger March, P.Geo., a professional geologist registered in the Province of Newfoundland & Labrador and a qualified person as defined by NI 43-101.

Concessions under the B2Gold option agreement are subject to B2Gold earning a 51% interest by completing C$8 million in expenditures by June 2014. Once the earn-in is complete, B2Gold may elect to carry an individual prospect within the concession area through to a Preliminary Economic Assessment for an additional 14% interest in the prospect.

Calibre Mining Corp. is an aggressive, TSX Venture Exchange listed company (TSX.V: CXB) that is focused on the acquisition, exploration and development of intrusive related deposits in Central America. Major shareholders of Calibre include gold producer Yamana Gold Inc. and investment fund Sun Valley Gold.

Calibre Mining Corp.

Signed "Robert Brown"

Robert D. Brown, B.Sc., MBA
President and CEO

For further information contact:

Robert Brown - Vancouver, Canada
604 681 9944
www.calibremining.com

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

Cautionary Note Regarding Forward Looking Statements
Safe Harbour Statement under the United States Private Securities Litigation Reform Act of 1995: Except for the statements of historical fact contained herein, the information presented constitutes "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements including but not limited to those with respect to the price of gold, silver or copper, potential mineralization, reserve and resource determination, exploration results, and future plans and objectives of the Company involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievement of Calibre Mining Corp. to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. There can be no assurance that such statements will prove to be accurate as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements.