A method and apparatus are described for the casting of a composite metal ingot having two or more separately formed layers of one or more alloys. An open ended annular mould is provided having a divider wall dividing a feed end of the mould into at least two separate feed chambers. For each pair of adjacent feed chambers, a first alloy stream is fed through one of the pair of feed chambers into the mould and a second alloy stream is fed through another of the feed chambers. A self-supporting surface is generated on the surface of the first alloy stream and the second alloy stream is contacted with the first stream. By carefully selecting conditions and positions where the alloy streams meet, a composite metal ingot is formed in which the alloy layers are mutually attached with a substantially continuous metallurgical bond.