A block of data is partitioned into a plurality of sub-blocks each including a logical array having rows and columns of data symbols, encoded using a row linear block code and a column linear block code. Each product codeword includes a logical array of code symbols having rows which include respective row codewords and columns which include respective column codewords. The product codewords are encoded by encoding groups of L symbols, using a rate-L/(L+M) linear block code to produce a plurality of (L+M)-symbol codewords which are logically arranged in nQ encoded blocks (where n is an integer greater than zero). Each of the nQ encoded blocks includes an array having rows and columns of code symbols in which each column includes a codeword of the column code.