  In this paper we investigate the structure of quasi-BCH codes. In the first
part of this paper we show that quasi-BCH codes can be derived from
Reed-Solomon codes over square matrices extending the known relation about
classical BCH and Reed-Solomon codes. This allows us to adapt the
Welch-Berlekamp algorithm to quasi-BCH codes. In the second part of this paper
we show that quasi-BCH codes can be seen as subcodes of interleaved
Reed-Solomon codes over finite fields. This provides another approach for
decoding quasi-BCH codes.
