Sirius Minerals Regulatory News (SXX)

For immediate release: 29 October 2010

Sirius Minerals Plc

("Sirius" or the "Company")

Significant Shareholders Update

Following the placing of September 2010, the Directors of Sirius Minerals Plc (AIM: SXX, OTC: SRUXY), the potash mining group, notify Shareholders that the Significant Shareholders list has today been updated on the Company website to reflect holdings as of 30 September 2010.

The information contained on the website is based on beneficial owners identified through independent third party research, notifications received by the Company and previously reported, and holdings of 3% or over that were listed on the Company's shareholder register as at 30 September 2010.

The Company continues to monitor beneficial owners through commissioned half yearly independent analysis and will update shareholders in accordance with the DTR and AIM requirements when required. Set out below is a copy of the information now available on the Company's website, wwww.siriusminerals.com.

Significant Shareholders

Share Capital 30 September 2010

·; Authorised share capital at 30 September 2010 1,500,000,000 Ordinary Shares of 0.25 pence each

·; Issued share capital at 30 September 2010 715,606,602 Ordinary Shares of 0.25 pence each

·; Treasury shares: None

The following interests amounting to 3% or more of the issued share capital of the Company are set out below. These include shareholders where the Company has been notified of the interest, where the Company has identified beneficial owners as a result of independent third party research first conducted in April 2010, and where the Company has on its register a shareholder of 3% or over as at 30 September 2010:

Beneficial owners (other than Directors and related parties)

Nominee shareholdings (Due to the fact that some of the beneficial owners may hold their shares in nominee accounts there may be a possibility of double counting):

Directors and related parties:

* Director

** Related Party

The above calculations include shares held by members of the directors' immediate family and children who are under age, shares held by trusts where they or members of their family and children are beneficiaries and related companies.

American Depository Receipts (ADR)

As at 30 September there were 22,588 ADR's with each ADR comprising 500 shares. This represents 11,294,000 Sirius ordinary shares or approximately 1.70% of the issued share capital.

Options

The following options have been granted and remain unexercised as at 30 September 2010:

Southern Star Investments Plc

• Number: 625,000• Exercise price: 4.5 pence• Date of expiry: 14 May 2011

Mr W D Doyle & Mr T A Pagano

• Number: 2,550,000• Exercise price: 17.5 pence• Date of expiry: 13 October 2012

Mr C Catlow (held by Broadscope Pty Ltd as trustee for the Catlow Family Trust)

• Number: 25,000,000 vested• Exercise price: 4.5 pence• Number: 25,000,000• Exercise price: 4.5 pence when the Company's share price closes above 15p per share for 5 consecutive trading days• Date of expiry: 6 April 2015

EAS Advisors LLC

• Number: 1,000,000 exercisable at 4p• Number: 1,000,000 exercisable at 6p• Number: 500,000 exercisable at 8p• Number: 500,000 exercisable at 10p• Number: 500,000 exercisable at 12p• Number: 500,000 exercisable at 14p• Number: 500,000 exercisable at 16p• Date of expiry: 31 March 2015

Mr. L Rodne, Mr. JT Starzecki, Mr. W Sonnenreich, Mr. P Griffiths

• Number: 8,500,000, of which:

- one third can be exercised from the date of granting,

- one third after twelve months from the date of granting,

- one third after twenty-four months from the date of granting,

subject to the recipient remaining employed by the Company at the date of exercise.

• Exercise price: 4.5p

• Date of expiry: 60 months from issue - 25 August 2015

- ENDS -

For further information, please contact:

Website: www.siriusminerals.com