UPDATE 1-Fresnillo wants review of MAG Silver valuation halt

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LONDON Feb 6 (Reuters) - Mexico's Fresnillo Plc (FRES.L) has asked Canadian regulators to review a move by its takeover target MAG Silver (MAG.TO) (MVG.A) to suspend a valuation of the company, which it alleged on Friday was a delaying tactic.

London-listed Fresnillo -- the world's biggest primary silver producer -- announced a $4.54 a share cash bid on Dec. 1 for the 80.2 percent of MAG it does not already own.

MAG Silver has said the $179 million buyout offer was too low and told Reuters in an interview on Jan. 30 it was stepping up prospecting activity to uncover as much metal as it can and attract either a white knight bid or a higher offer from Fresnillo. [ID:nN30529296]

Fresnillo said its unit Fresbal asked the Ontario Securities Commission to review the decision by MAG Silver's independent committee's decision to suspend work on the valuation.

MAG Silver said on Feb. 1, the valuation was halted because Fresnillo had failed to provide key information, a charge Fresnillo denied.

"Fresbal is disappointed with what it views as an inappropriate delaying tactic by MAG Silver," Fresnillo said in a statement.

"Fresbal intends to take the necessary steps to enable MAG Silver shareholders to receive the offer in compliance with all laws as soon as practicable."

By 1104 GMT, Fresnillo shares were up 6 percent to 374 pence, outperforming a 2.4 percent rise in the UK mining index .FTNMX1770.

MAG Silver's shares closed on Thursday at $6.01 on the Amex exchange, a third higher than Fresnillo's bid.

The shares have been driven by expectations of a white-knight bid, and also by a steady stream of strong drill results, which have stoked optimism about the prospects for the firm's properties in silver-rich Mexico.

MAG, whose main asset is a 44 percent stake in the Juanicipio property -- a joint venture with Fresnillo -- is now ramping up exploration at its other assets to try to generate as much good news as possible.

Fresnillo is a unit of Mexico's Penoles (PENOLES.MX) that was spun off last May. (Reporting by Eric Onstad; Editing by Andrew Macdonald)