NexGen's Joint Venture Partner, Forum Uranium Corp. Reports Wide Zone of Continuous, Shallow Uranium Mineralization at Otis West, Northwest Athabasca Project

VANCOUVER, BRITISH COLUMBIA--(Marketwired - June 5, 2013) -NexGen Energy Ltd. (TSX VENTURE:NXE) ("NexGen" or the "Company") is pleased to announce that its joint venture partner, Forum Uranium Corp., has reported shallow uranium mineralization from assayed drilling at Otis West (previously reported gamma ray scintillometer radioactivity in the news release dated April 10, 2013), part of the Northwest Athabasca Project. Grades of up to 1.80% U3O8 were intersected in 5 of 9 holes drilled on this target immediately south of the Maurice Bay deposit. The mineralized zone remains open to depth and to the east.

This is the fourth target drilled on the property that has intersected basement-hosted uranium mineralization typical of uranium deposits in the western Athabasca Basin such as Patterson Lake South, Cluff Lake and Shea Creek.

Highlights

• 24.5 metres grading 0.21% U3O8, including 1.80% U3O8 over 0.5 metres
• Mineralization in 5 holes from two drill fences at 50 metre spacing
• Mineralization remains open to the east along an unconformity offset

Otis West lies on the south side of the Maurice Bay deposit (historical resource* of 1.5 million pounds of uranium grading 0.6% U3O8) in a strong gravity low. Mineralization is hosted mainly within basement rocks along a major fault (the Otis fault) parallel to the Maurice Bay fault (Figure 1). This zone was intersected in diamond drillholes NWA-60 and 61 and by drillholes NWA-56, 63 and 64 on a section 50 metres further east. The mineralization shows a vertical extent of 110 metres and remains open to the east (Figure 2). Very strong boron values in the overlying sandstone (up to 1.18%) are associated with this mineralization. Boron is a strong pathfinder indicator for economic uranium deposits in the Athabasca Basin.

Future drill programs will continue drilling along the Otis Fault to the east.

A 1.5 million pound historical uranium resource grading 0.6% U3O8 for the Maurice Bay deposit, as reported by Saskatchewan Industry and Resources, Miscellaneous Report 2003-7 has not been calculated or classified under the specifications of National Instrument 43-101 and should not be relied upon.

Quality Assurance and Quality Control

Core samples are collected and shipped in sealed containers to the Saskatchewan Research Council, an ISO/IEC 17025:2005 (CAN-P-4E) certified laboratory for geochemical analysis using the Uranium ICP Package. This package is the preferred analytical technique for detecting uranium and pathfinder elements in the alteration halos of unconformity-type uranium deposits in the Athabasca Basin.

Ken Wheatley, P.Geo. (Saskatchewan, NWT/Nunavut), Forum's Vice President, Exploration, a "qualified person" for the purposes of National Instrument 43-101 - Standards of Disclosure for Mineral Projects has reviewed and approved the contents of this news release.

To view the map associated with this press release, please visit the following link: http://media3.marketwire.com/docs/NexGen-NXE.pdf.

Figure 1: Unconformity Contour Map of the Maurice Bay Deposit Area. Blue to black colours are deep sandstone (70 to 120m). Yellow to red colours are 0 to 50m deep sandstone. Yellow stars are historical drillholes, the majority of them stopping at or near the unconformity contact. The red dots are Forum drill holes from 2013 in the Otis West area. The Maurice Bay deposit, the high grade A Zone mineralization and the Otis West mineralization are all associated with an offset (fault) in the unconformity.

NW Athabasca Joint Venture

The NW Athabasca project is a joint venture between NexGen Energy Ltd. and Forum Uranium Corp., as to 60% and Cameco Corporation as to 27.5% and AREVA Resources Canada Inc. as to 12.5%.

About NexGen

NexGen is a British Columbia corporation with a focus on the acquisition, exploration and development of Canadian uranium projects. NexGen has a highly experienced team of exploration professionals with a track record in the discovery of unconformity-style uranium deposits in Canada.

NexGen owns a portfolio of highly prospective uranium exploration assets in the Athabasca Basin, Saskatchewan, Canada, including, an option to earn a 70% interest in the Radio Project, immediately adjacent to Rio Tinto's Roughrider Deposit and a 100% interest in Rook 1, immediately adjacent to the north east of Patterson Lake South.

Forward-Looking Information

This news release contains "forward-looking information" within the meaning of applicable Canadian securities laws. Generally, but not always, forward looking information is identifiable by the use of words such as "expects" "anticipates", "believes", "projects", "plans", and similar expressions. Forward-looking information is prospective and by its nature requires the Company to make certain assumptions and is subject to inherent risks and uncertainties. Such information is not a guarantee of future performance and undue reliance should not be placed on forward-looking information. Although the assumptions made by the Company in providing forward looking information are considered reasonable by management at the time the forward-looking information is given, there can be no assurance that such assumptions will prove to be accurate. Forward-looking information also involves known and unknown risks and uncertainties, which may cause actual results in future periods to differ materially from any projections of future results expressed or implied by such forward-looking information, including changes in exploration programs based upon results of exploration; future prices of metal; availability of third party contractors; availability of equipment and supplies; failure of equipment to operate as anticipated; accidents, effects of weather and other natural phenomena; environmental risks; community relations; and delays in obtaining governmental approvals or financing. There can be no assurance that forward-looking information will prove to be accurate, as actual results and future events could differ materially from those anticipated, estimated or intended. NexGen undertakes no obligation to update or reissue forward-looking information as a result of new information or events except as required by applicable securities laws. The reader is cautioned not to place undue reliance on forward-looking information.