Offer Update

Antofagasta PLC
18 April 2006





                                ANTOFAGASTA PLC


             Antofagasta to declare its takeover offer for Tethyan
                  unconditional when its interest exceeds 50%





18 April 2006



Antofagasta PLC ('Antofagasta') announces today that its recommended takeover
offer for Tethyan Copper Company Limited ('Tethyan') will be declared
unconditional when its relevant interest in Tethyan shares exceeds 50%.



As of today, Antofagasta has a relevant interest in Tethyan of 45%.



The Board of Tethyan continues to unanimously recommend that all shareholders
accept the Antofagasta offer (in the absence of superior offer).




                                                 Enquiries - Santiago

Enquiries - London

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

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

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

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




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