In this paper, we consider the case where data from a relatively large number of sources are to be transmitted to a single destination. We suppose that there is no communication between the sources and thus each source encodes its data independently using the same systematic linear block code. The codewords transmitted from the sources to the destination are eavesdropped by a relay. A product code is built at the relay, with rows being the possibly erroneous source codewords, using a second systematic linear block code as column encoder. The resulting additional redundancy is then transmitted to the destination. The product code matrix is pieced together from source codewords and relay redundancy received by the destination. Significant additional coding gain is achieved on the additive white Gaussian noise (AWGN) channel. Performance on the correlated flat Rayleigh fading channel is also given for different correlation coefficients yielding large diversity orders.