How to give AP the ability to edit supplier site contact details whilst still disallowing Supplier a

Oracle e-Bus question. Applies equally to 11i as 12.

We segregate Vendor masterfile maintenance from the AP function, and local buying functions.

However the AP function are closest to many supplier  Site contacts, and buyers are closer to other site contacts.

Is there a way we can allow these functions the ability to create/update site contacts without letting them create suppliers or sites or address maintenance activities?