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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING
FIRM

To the Board of Directors and Shareholders of Augusta
Resource Corporation

We have audited Augusta Resource Corporations internal control over financial reporting as of December 31, 2011,
based on criteria established in Internal Control - Integrated Framework issued by
the Committee of Sponsoring Organizations of the Treadway Commission (the COSO
criteria). Augusta Resource Corporations management is responsible for maintaining effective
internal control over financial reporting, and for its assessment of the
effectiveness of internal control over financial reporting included in the
accompanying Managements Assessment of Internal Control over Financial
Reporting. Our responsibility is to express an opinion on  Augusta Resource Corporations internal control over financial reporting based on our audit.

We conducted our audit in accordance with the standards of the
Public Company Accounting Oversight Board (United States). Those standards
require that we plan and perform the audit to obtain reasonable assurance about
whether effective internal control over financial reporting was maintained in
all material respects. Our audit included obtaining an understanding of internal
control over financial reporting, assessing the risk that a material weakness
exists, testing and evaluating the design and operating effectiveness of
internal control based on the assessed risk, and performing such other
procedures as we considered necessary in the circumstances. We believe that our
audit provides a reasonable basis for our opinion.

A companys internal control over financial reporting is a
process designed to provide reasonable assurance regarding the reliability of
financial reporting and the preparation of financial statements for external
purposes in accordance with generally accepted accounting principles. A
companys internal control over financial reporting includes those policies and
procedures that (1) pertain to the maintenance of records that, in reasonable
detail, accurately and fairly reflect the transactions and dispositions of the
assets of the company; (2) provide reasonable assurance that transactions are
recorded as necessary to permit preparation of financial statements in
accordance with generally accepted accounting principles, and that receipts and
expenditures of the company are being made only in accordance with
authorizations of management and directors of the company; and (3) provide
reasonable assurance regarding prevention or timely detection of unauthorized
acquisition, use or disposition of the companys assets that could have a
material effect on the financial statements.

Because of its inherent limitations, internal control over
financial reporting may not prevent or detect misstatements. Also, projections
of any evaluation of effectiveness to future periods are subject to the risk
that controls may become inadequate because of changes in conditions, or that
the degree of compliance with the policies or procedures may deteriorate.

In our opinion, Augusta Resource Corporation maintained, in all material
respects, effective internal control over financial reporting as of December 31,
2011, based on the COSO criteria.

We also have audited, in accordance with the standards of the
Public Company Accounting Oversight Board (United States), the consolidated
financial statements of Augusta Resource Corporation, which comprise the
consolidated statements of financial position as at December 31, 2011 and 2010,
and January 1, 2010, and the consolidated statements of comprehensive profit,
changes in equity and cash flows for the years ended December 31, 2011 and 2010
of Augusta Resource Corporation and our report dated March 19, 2012, expressed an unqualified
opinion thereon.

|Vancouver, Canada | /s/ Ernst & Young LLP
|----------------- | ---------------------
|March 19, 2012    | Chartered Accountants

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