Mountain Province Diamonds Adopts New Shareholders Rights Plan

TORONTO and NEW YORK, September 9, 2010 -

    Shares Issued and Outstanding: 72,107,923
    TSX: MPV
    NY- AMEX: MDM

Mountain Province Diamonds Inc. ("Mountain Province" or the "Company")
(TSX: MPV, NY-AMEX: MDM) announced today that has entered into a new
shareholder rights plan (the "Plan") to update its existing plan, subject to
all necessary regulatory and shareholder reconfirmation. The Plan is designed
to ensure that the Company's shareholders are treated fairly in the event of
a take-over bid for the Company's common shares and that the Company's Board
of Directors and shareholders will have adequate time to evaluate any
unsolicited take-over bid and, if appropriate, to evaluate and pursue other
alternatives to maximize shareholder value.

The Plan was not adopted in response to any actual or threatened
take-over bid or other proposal from a third party to acquire control of the
Company.

The Plan is effective as of September 9, 2010 (the "Effective Date"),
subject to the approval of the Toronto Stock Exchange for which application
has been made. In accordance with the requirements of the Toronto Stock
Exchange, the Company's shareholders will be asked to confirm the Plan at the
annual general and special meeting of shareholders to be held on November 18,
2010. If approved by shareholders, the Plan will be in effect until the sixth
anniversary of the Effective Date, but must be reconfirmed by shareholders at
the 2013 annual general meeting.

At the close of business on the Effective Date, one right (a "Right")
will be issued and attached to each common share of the Company outstanding
at that time. A Right will also attach to each common share of the Company
issued after the Effective Date. If shareholders do not confirm the Plan at
the upcoming general meeting, the Plan and the Rights will terminate and
cease to be effective.

The Plan is similar to shareholder rights plans recently adopted by
several other Canadian companies. The Plan is not intended to block take-over
bids. The Plan includes "Permitted Bid" provisions which will prevent the
dilutive effects of the Plan from operating if a take-over bid is made by way
of a take-over bid circular that, among other things, remains open for a
minimum of 60 days and is accepted by a specified proportion of the common
shares held by independent shareholders. The Plan will be triggered by an
acquisition, other than pursuant to a Permitted Bid, of 20% or more of the
outstanding common shares of the Company or the commencement of a take-over
bid that is not a Permitted Bid.

About Mountain Province

Located in Canada's Northwest Territories, Gahcho Kué is one
of the largest new diamond projects under development globally. The project
consists of a cluster of kimberlites, three of which have an indicated
resource of approximately 30.2 million tonnes grading at 1.67 carats per
tonne (approximately 50.5 million carats) and an inferred resource of
approximately 6 million tonnes grading at 1.73 carats per tonne
(approximately 10.3 million carats). Mineral resources that are not mineral
reserves do not have demonstrated economic viability.

Note to U.S. Investors

This press release describes minerals which have been
classified as "indicated resources" and "inferred resources" under National
Instrument 43-101. We advise U.S. investors that while those terms are
recognized and required by Canadian regulations, the U.S. Securities and
Exchange Commission do not recognize them. "Inferred resources" have a great
amount of uncertainty as to their existence, and great uncertainty as to
their economic and legal feasibility. It cannot be assumed that all or any
part of an inferred mineral resource as defined under National Instrument
43-101 will ever be upgraded to a higher category. Under Canadian rules,
estimates of inferred mineral resources may not form the basis of feasibility
or pre-feasibility studies, except in rare cases. U.S. investors are
cautioned not to assume that any part or all of mineral deposits in these
categories will ever be converted into reserves nor that part or all of an
inferred resource exists, or is economically or legally minable.

Cautionary Statement Regarding Forward-Looking Information

Certain statements in this press release relating to the
Company's capital management, development projects, exploration properties,
project expenditures and business plans are "forward-looking statements"
within the meaning of securities legislation. The Company does not intend,
and does not assume any obligation, to update these forward-looking
statements. These forward-looking statements represent management's best
judgment based on current facts and assumptions that management considers
reasonable, including that operating and capital plans will not be disrupted
by issues such as mechanical failure, unavailability of parts, labour
disturbances, interruption in transportation or utilities, or adverse weather
conditions, that there are no material unanticipated variations in budgeted
costs, that contractors will complete projects according to schedule, and
that actual mineralization on properties will not be less than identified
mineral reserves. The Company makes no representation that reasonable
business people in possession of the same information would reach the same
conclusions. Forward-looking statements involve known and unknown risks,
uncertainties and other factors which may cause the actual results,
performance or achievements of the Company to be materially different from
any future results, performance or achievements expressed or implied by the
forward-looking statements. In particular, fluctuations in the price of
copper or in currency markets could prevent the Company from achieving its
targets. Readers should not place undue reliance on forward-looking
statements. More information about risks and uncertainties affecting the
Company and its business is available in Mountain Province's most recent
Annual Information Form and other regulatory filings which are posted on
sedar at www.sedar.com.

    FOR FURTHER INFORMATION, PLEASE CONTACT:

    Mountain Province Diamonds Inc.
    Patrick Evans, President and CEO
    Tel: +1-416-670-5114

FOR FURTHER INFORMATION, PLEASE CONTACT: Mountain Province Diamonds Inc., Patrick Evans, President and CEO, Tel: +1-416-670-5114.