Toronto, Ontario ¨C May 14, 2013 ¨C Sierra Metals Inc. (TSX-V:SMT) (BVL:SMT) (¡°Sierra Metals¡± or the ¡°Company¡±; previously Dia Bras Exploration) is pleased to announce that drilling has encountered wide zones of mineralization in both the Upper and Lower Skarn horizons located 600 m northwest of the major ore-hosting zones of the Bolivar (Alta Ley) Mine. In addition, step-out drilling from the El Gallo deposit has extended that mineralized zone 600 m to the northeast with high grades of zinc in the Upper Skarn horizon.

Press Release Highlights

• At Bolivar Northwest (¡°Bolivar NW¡±), drill hole DB13B433 cut 7.05 m core length averaging 1.552 g/t gold, 53 g/t silver, 0.55% copper and 1.15% zinc, including 5.5 m averaging 1.914 g/t gold, 64 g/t silver, 0.66% copper and 1.38% zinc.
   


• Drilling in the Bolivar NW area has extended mineralization 600 m from Alta Ley over an area of 600 m by 250 m, which is open to the northwest and northeast.
   


• In the Step Out area northeast of El Gallo, drill hole DB12B416 cut 10.8 m core length averaging 0.89% copper and greater than 9.66% zinc, including 3.2 m averaging 2.91% copper and greater than 30% zinc (30% being the assay limit; re-assays pending).
   


• The Step Out area is located 600 m northeast of the El Gallo mining area near the Incre¨ªble Mine where two prominent NNW-trending faults, the Nathalie and Fernandez Faults, converge on the area.

Daniel Tellechea, President and CEO of Sierra Metals, commented: ¡°Sierra Metals continues to expand the Bolivar ore deposits through its aggressive exploration drilling program. These results support our contention that the Bolivar mine is only partially explored and that significant additional mineralization remains to be discovered. While our recent reserves statement provided a snapshot of Bolivar¡¯s mineralization at that time, we expect to increase reserves and resources during this year with the objective of commissioning a NI 43-101 update at the end of 2013.¡±

Recent Drilling Results

Bolivar NW Area: This area (Figure 1) is located northwest of the Alta Ley Mine and hosts manto-type mineralization in both the Upper and Lower Skarns, which are the prominent mineralized horizons in the Bolivar Mine area. Very little drilling had been done in this area before this year and results to date indicate the mineralized horizons extend hundreds of meters to the northwest and northeast.

Assay results are shown in the table below:

Note *: all holes have prefix DB13B

Sections DB13B425 and DB13B433 (Figure 2 & Figure 3) show the relationships of these drill holes and their mineralized intervals. From the Alta Ley mine to the northwest, the mineralized horizons extend for at least 600 m to the northwest and for a width of at least 250 m.

¡°Step Out¡± Area: This area is located 600 m northeast of the El Gallo deposit which is one of the areas currently being mined by the Company. These drill holes were placed where the Nathalie and Fernandez Trend faults converge, and where the Incre¨ªble breccia pipe occurs. The high zinc values in these holes demonstrate that the Upper Skarn horizon, the same horizon that hosted high grades of copper and zinc in the Alta Ley Mine, is strongly mineralized in this area.

For example, the intercepts in holes 416 & 424, combined with 426 (assays pending) indicate a 100-m long zone of Upper Skarn zinc mineralization that is open both directions along strike and to depth. Additional drilling will be done to determine the extent of this zone. These holes were drilled towards the Incre¨ªble breccia pipe in a north-westerly direction and were not oriented properly to test mineralization related to the Nathalie Fault but did intercept ¡°high-value¡± skarn mineralization of the type targeted in the Company¡¯s drill program for 2013. These intercepts, however, are in the area that is inferred to host ¡°high-value¡± deposits, namely in the vicinity of the Nathalie Fault.

New holes in progress are oriented specifically to test for ¡°high-value¡± deposits and drilling is planned to continue through 2013 with the objective of discovering ¡°high-value¡± deposits, namely deposits with Cu+Zn grades of 15-20%, the type encountered in drill hole 416.

Drill results include the following:

Note *: all holes have prefix DB12B; ** assay upper limit is 30.00% zinc

Implications

Drilling up to 600 m both to the northwest and northeast of the Company¡¯s active mining areas of El Gallo and Alta Ley has shown potentially mineable ore grades and widths in the Upper and Lower Skarn horizons, clearly demonstrating that the limits of mineralization have not been reached.

Management of Sierra Metals believes that the deposits at El Gallo, Alta Ley and other areas have additional potential for expansion and the Company is conducting an aggressive drilling program to explore these areas further.

The ongoing drilling program will continue to test these new mineralized horizons and high value targets. Two drills are currently in operation on the surface and one drill underground; 14,970 meters are scheduled to be drilled in 2013.

The 7.46 million tonnes of Proven and Probable Reserves grading 19.52 g/t Ag, 0.76% Cu, 0.33% Zn and 0.12 g/t Au (see press release of April 24, 2013), and 15.40 million tonnes of Measure and Indicated Resources grading 19.45 g/t Ag, 0.79% Cu, 1.06% Zn and 0.24 g/t Au (see press release of August 30, 2012) at Bolivar represent a significant but unknown portion of the extensive mineralization that occurs in the area.

Method of Analysis

Samples were prepared at the ALS Chemex lab facility in Chihuahua, Mexico, and analyzed by ICP and AA methods at their facilities in Vancouver, Canada. Diamond drill samples sent for analysis consisted of half HQ-size and NQ-size diamond core split on site, prepared by the ALS Chemex sample preparation laboratory in Chihuahua, Mexico, and assayed for Au by 50 g fire assay with AA finish, and for Ag by AA on 50 g split sample at the ALS Chemex North Vancouver Laboratory. Assays for Pb, Zn and Cu are analyzed by Induction Coupled Plasma (ICP) at ALS Chemex.

Quality Assurance

The technical content of this news release has been approved by Thomas L. Robyn, Ph.D., CPG, RPG, a Qualified Person as defined in NI 43-101 and Senior Vice President, Exploration, for Sierra Metals Inc.

About Sierra Metals

Sierra Metals Inc. is a Canadian mining company focused on precious and base metals from its Yauricocha mine in Peru, and its Bolivar and Cusi mines in Mexico. In addition, Sierra Metals is exploring several precious and base metal targets in Peru and Mexico. Projects in Peru include Adrico (gold), Victoria (copper-silver) and Ipillo (polymetallic) at the Yauricocha Property in the province of Yauyos and the San Miguelito gold properties in Northern Peru. Projects in Mexico include Bacerac (silver) in the state of Sonora, La Verde (gold) at the Batopilas Property in the state of Chihuahua, and Las Coloradas (silver) at the Melchor Ocampo Property in the state of Zacatecas.

The Company¡¯s shares trade on the Bolsa de Valores de Lima and TSXV under the symbol ¡°SMT¡±.

For further information on Sierra Metals, please visit www.sierrametals.com or contact:

This press release does not constitute an offer to sell or solicitation of an offer to buy the securities in the United States or any other jurisdiction. The Common Shares will not be and have not been registered under the United States Securities Act of 1933, as amended, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements.

Neither the TSXV nor its Regulation Services Provider (as that term is defined in policies of the TSXV) accepts responsibility for the adequacy or accuracy of this release.

Forward-Looking Statements