Dacia Duster hybrid version: noise when engine engages

We live in France. On our new (600kms) hybrid duster there is an audible clunk noise when the 1.8cc petrol engine engages and even sometimes when it disengages. The display showing where the power is coming/going has a delay on it so is not much of a help at exactly knowing when this happens. The noise does not seem to originate from under the bonnet. It occurs in all drive modes. Anyone have an explanation?