Calibre Announces Drilling Update At Borosi Gold-Copper Concessions, Nicaragua

May 4, 2010

Vancouver, British Columbia: Calibre Mining Corp. (TSX-V: CXB) (the "Company" or "Calibre") is pleased to announce that the first round of diamond drilling has been completed at the Bambana copper-gold project and has commenced at the Riscos de Oro gold-silver project. As announced on April 22, 2010, a second drill rig is active on the La Luna gold-silver project. The Bambana, Riscos de Oro and La Luna projects are located within Calibre's 100% owned Borosi gold-copper concessions in northeast Nicaragua.

Bambana Project
Three diamond drill holes are completed at the Bambana project and results will be reported when received and compiled. The drill program is testing two areas. The first area is a 500 metre by 300 metre area associated with artisanal gold workings and a small prospecting pit. The area has anomalous gold and copper soil anomalies and coincident geophysics. Sampling of the prospecting pit by Calibre returned grades of 1.64 g/t gold, 1,645 g/t silver and 29.9% copper over 0.90 metres. The second area is drill testing a northeast trending structure that is associated with gold and copper soil anomalies and geophysical targets.

The Bambana project lies four kilometres northwest of the past producing Santa Rita copper mine, a copper skarn deposit that is estimated to have produced 305 million pounds of copper over the mine life1.

Riscos de Oro Project
Diamond drilling has commenced at the Riscos de Oro project and will focus on two targets: the main Riscos de Oro vein that contains historic open pit and underground workings; and a possible parallel vein located 800 metres to the northwest.

The down dip vein extensions at the historic Riscos mine will be drill tested approximately 200 metres below surface. Historic drilling by Rosario Resources from the zone between the 46 metre and 93 metre abandoned development levels reported intercepts of 9.43 g/t gold and 163 g/t silver over 6.2 metres (DDH SG-16), 14.5 g/t gold and 174 g/t silver over 3.79 metres (DDH SG-17) and 8.06 g/t gold and 563 g/t silver over 4.1 metres (DDH SG-4)2. The drill program will also follow up on the northeast and southwest extensions of the Riscos vein trend as well as the parallel zone northwest of the Riscos mine.

2009/2010 Exploration Program at Borosi
The planned diamond drill program at the Borosi concessions consists of drill testing three projects: the Bambana project, the La Luna project and the Riscos de Oro project. In addition, systematic exploration of other high priority prospects at Borosi will be ongoing to further define drill targets.

The Borosi concessions cover approximately 71,000 hectares within the historic Mining Triangle of Nicaragua. The concessions are subject to an option agreement, whereby B2Gold may earn an initial 51% in the Borosi concessions by completing C$8 million in exploration expenditures over a period of three years. The Borosi exploration budget through July 2010 is C$2.5 million, with Calibre acting as operator.

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.

Calibre Mining Corp. is an aggressive, well financed, TSX Venture Exchange listed company (TSX.V: CXB) that is focused on the acquisition, exploration and development of gold and copper deposits in Central America. Major shareholders of Calibre include gold producers Yamana Gold Inc. and Kinross Gold Corp.

1From Arengi et al (2002).
2 Rosario Resources company records on Riscos de Oro. Circa 1975 to 1977. No drill core remains from the Rosario drill programs and, therefore, Calibre is unable to independently verify the accuracy of these historic results.


Calibre Mining Corp.
Signed "Robert Brown"

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


For further information contact:
Joyce Musial -- 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 Harbor 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.

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