hey Paul,
i dont know if all this components are crossplattform but its up to you to check this ;>
TZIP
ZipForge
KAZip
Abbrevia
you can also look at
Torry
EDIT: oh im not familar with what FreePascal can use or not cause i use Delphi :/
EDIT2: after reading and testing some stuff i would recomment Abbrevia cause it fit all what you asked for
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