Offer Update

Antofagasta PLC
28 March 2006

                                ANTOFAGASTA PLC



Update: Recommended cash offer for Tethyan Copper Company Limited ('Tethyan')



London, 28 March 2006 - Antofagasta PLC ('Antofagasta') is pleased to note the
announcement issued yesterday by Skafell Pty Ltd ('Skafell') confirming that it
will allow its takeover offer for Tethyan to lapse on 3 April 2006 and that
Skafell has sold all of its Tethyan shares.

Once Skafell's offer closes on 3 April, Antofagasta's A$1.40 recommended cash
offer will be the only takeover offer open for acceptance by Tethyan
shareholders.  The Board of Tethyan is unanimously recommending that Tethyan
shareholders accept Antofagasta's offer (in the absence of a superior offer).

Antofagasta encourages all Tethyan shareholders to accept its offer as soon as
possible.

Antofagasta is also considering its options with respect to the claw-back right
over certain Tethyan mineral interests.  Under its agreement with BHP Billiton,
Antofagasta may either:

(i)             Purchase the claw-back right from BHP Billiton at any time
during the currency of its offer(1) thereby entitling Antofagasta to directly
acquire 70% of Tethyan's economic interest in the Western Porphyries (which
currently hosts the vast majority of the contained copper-gold resource at Reko
Diq); or

(ii)           Upon securing control of Tethyan, procure that Tethyan enters
into an agreement with BHP Billiton terminating the claw-back right, thus
preserving its full benefit in Reko Diq's copper-gold resource.

Rothschild is advising Antofagasta in relation to this transaction.

Note: (1) Following the satisfaction or waiver of the Other Regulatory Approvals
condition under Antofagasta's takeover offer.


Enquiries - London                               Enquiries - Santiago

Antofagasta PLC                                  Antofagasta Minerals S.A.
Tel: [phone]                            Alejandro Rivera
www.antofagasta.co.uk                            Tel: [phone]
                                                 Email: [e-mail]

Desmond O'Conor
Email: [e-mail]                 Enquiries - Australia


Bankside Consultants                             N M Rothschild & Sons (Australia) Ltd (financial advisers)
Tel: [phone]                            Tel: [phone]
Mob: [phone]                            Marshall Baillieu
                                                 Chris Forman

Keith Irons
Email: [e-mail]                        Jackson Wells Morris (public relations advisers)
                                                 Tel: [phone]
                                                 Benjamin Haslem
                                                 Jakob Webster


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