General update

6 August 2013

Sirius Minerals Plc

General update

§ The Sirius York Potash Project is a Tier 1 asset with projected cash costs that would place it at the bottom of the global potash cost curve

§ Robust economics will underpin the financing and development of the 2.66 billion tonne inferred polyhalite resource

§ Increasing customer demand and positive market engagement demonstrates value of the product and the global demand for large volume long-term independent supply

The Directors of Sirius Minerals Plc (AIM: SXX, OTCQX: SRUXY) ("Sirius" or the "Company") comment on the latest developments in the potash industry and a general update on the York Potash Project planning approval process.

Chris Fraser, Managing Director and CEO of Sirius, comments:

"There is little doubt that potential reductions in MOP prices present a problem for existing high cost producers, which could in turn lead to further supply consolidation, but the York Potash Project has a robust business model to underpin its financing and development into a long term independent supplier.

"The volatility caused in the potash market by this speculation perfectly demonstrates the dangers of the supply of such an important mineral being concentrated amongst a small number of producers and re-emphasises the need for new, lost-cost, long-life projects that can operate outside the existing restricted market."

Robust financial case for the York Potash Project

The Company notes with interest the wide-spread commentary on the near-term future of potash prices following comments from Uralkali. The York Potash Project is financially robust on a range of pricing scenarios and has an operating cost projected to be at the bottom of the industry cost curve. This is an important factor in being a Tier 1 asset as it provides long-term resilience against possible future pricing volatility.

The recent statements from Uralkali relate to the potassium chloride (muriate of potash or "MOP") market and have caused concern and uncertainty in the market. The price scenarios articulated by Uralkali and other market commentators are of greater concern for those operations that have high operating costs.

The Company highlights the following points:

·; The price reductions being discussed are expected by most commentators to be a short to medium term phenomenon. This is due to the expected increase in demand stimulated at lower prices, the potential reduction in supply from high cost producers and the cancelation of many greenfield and brownfield MOP development projects; and

·; Whilst the potassium component of polyhalite is a significant part of the product value, it is the value of the other nutrients of sulphur, magnesium and calcium and the absence of chloride and the fact it is certified for organic use that is driving global demand. These other nutrients and product attributes provide a product value buffer over the basic MOP price.

For modelling purposes at the time of the release of the pre-feasibility study in December 2012, the Company used a price of US$150/t FOB Teesside as the central price in a series of sensitivities. This price already represents a 20% discount to the implied polyhalite nutrient value.

A range of sensitivities were provided at the time in December which highlighted the strength of the project to not only endure but also prosper in times of depressed pricing. For example, at assumed flat polyhalite sale price of US$112 per tonne, representing a 25% discount from the US$150 per tonne level, delivered a net present value ("NPV") of $1.2bn for Phase 1 production only (5 million tonnes per annum). On this downside scenario the project NPV is still significantly higher than any other greenfield potash project globally and is likely to be significantly higher than a number of producing projects despite the capital cost to develop the project.

York Potash approvals update

Further to the announcement of 18 July 2013, the Company has held meetings with the North York Moors National Park Authority ("NYMNPA" or "the Authority") and other key statutory stakeholders. The discussions were productive and the Company continues to work collaboratively with the Authority to work through the outstanding issues previously raised by the NYMNPA's consultants.

No timetable has yet been announced for a new decision as the Company wishes to ensure any new timeframe is clearly laid out and achievable. It is currently undertaking a gap analysis of the work provided to date and believes the report compiled by the Authority's consultants on the Company's Environmental Statement effectively provides a checklist for issues to ensure there are no remaining environmental concerns.

The Company believes there are no significant or fundamental environmental issues that deliver unacceptable impacts that cannot either be addressed or mitigated, so is confident that its revised Environmental Statement will be both legally robust and provide a good level of comfort over the likely impact of the plans. Many of the issues raised relate to construction impact and as a result Gordon Cowe, Development Director, will lead the work to provide the additional information to the National Park. The Company's discussions with the Authority will continue and a number of new or additional specialist consultants are being employed to assist with this process.

Broker update

The Company's brokerage contract with Jefferies Hoare Govett ("Jefferies") has been terminated and Jefferies will cease to be a broker on 26 August 2013 at the end of the contractual three-month notice period.

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About Sirius Minerals Plc

Sirius Minerals is a globally diversified potash development company. Its primary focus is to bring on stream major potash mining facilities through the acquisition and development of projects overlying recognised potash deposits. Today it holds properties in the United Kingdom (North Yorkshire) and the United States (North Dakota). Incorporated in 2003, Sirius Minerals' shares are traded on the London Stock Exchange's AIM market. Its shares are also traded in the United States on the OTCQX through a sponsored ADR facility. Further information on the Company can be found at www.siriusminerals.com.