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   [LOGO]                                                         Exhibit(a)(20)

GRUPO MEXICO
Av. Baja California #200, Mexico City 06760

                                                               NEWS RELEASE

                                                           FOR IMMEDIATE RELEASE
                                                           ---------------------

CONTACTS
- --------

GRUPO MEXICO, S.A. de C.V.                            ABERNATHY MacGREGOR FRANK
Daniel Tellechea                                      Chuck Burgess
011-525-574-8483                                      212-371-5999
Eduardo Gonzalez
011-525-574-8422



GRUPO MEXICO EXTENDS EXPIRATION DATE ON TENDER OFFER
- ----------------------------------------------------

MEXICO CITY (NOVEMBER 11, 1999) - Grupo Mexico, S.A. de C.V. today announced
that, in accordance with the terms of its Merger Agreement with ASARCO
Incorporated (NYSE:AR), it is extending the expiration date of its
outstanding tender offer until Friday, November 12, 1999, at 12:00
midnight New York City time. The tender offer previously had been scheduled
to expire on Wednesday, November 10, 1999, at 12:00 midnight New York City time.
As of 12:00 midnight New York City time on November 10, 1999, 35,780,174
shares of ASARCO common stock had been tendered under the terms of the Offer
which, when added to the shares already owned by Grupo Mexico, represent
approximately 89.5% of the shares of ASARCO common stock outstanding.

The Merger Agreement requires Grupo Mexico to extend the tender offer for up
to three business days if at the initially scheduled expiration date of
November 9, 1999 all of the conditions to the Offer are satisfied or waived,
but the number of shares of ASARCO common stock tendered, together with the
shares owned by Grupo Mexico and its subsidiaries, constitutes 80% or more, but
less than 90%, of the outstanding shares of ASARCO common stock. Grupo Mexico
had previously extended the expiration date of the tender offer until 12:00
midnight in New York City time on November 10, 1999. ASARCO has informed Grupo
Mexico that, at the close of business on November 10, 1999, 39,957,177 shares
of ASARCO common stock were issued and outstanding.


Under applicable law, Grupo Mexico can effect a short-form merger without a
shareholder vote if it owns at least 90% of the outstanding ASARCO shares.
Accordingly, Grupo Mexico and ASARCO have agreed that Grupo Mexico will again
extend the tender offer by one business day, and then will reevaluate whether a
further one day extension is warranted in order to obtain the tender of 90% of
the shares needed to effect a short-form merger.

                                   --more--

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Chase Securities Inc. served as financial advisor to Grupo Mexico and has
arranged the financing for the transaction. Brown & Wood LLP and Santamarina
y Steta served as legal advisors to Grupo Mexico.

Grupo Mexico is a diversified mining company that ranks among the world's
largest and lowest-cost copper, zinc and silver producers. The company's
operations include mining, smelting and refining. Grupo Mexico also owns 74%
of and operates in partnership with Union Pacific (26%), the largest and most
profitable railroad in Mexico.

Note: Statements in this press release include "forward looking statements" that
express expectations of future events or results. All statements based on future
expectations rather than on historical facts are forward-looking statements that
involve a number of risks and uncertainties, and the company cannot give
assurance that such statements will prove to be correct.

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