Help identifying strange nocturnal creature noise?

We were camping in the Loire region of France this year, and during the night a strange noise came from outside our tent. It got closer - it was a noise like someone twanging the string on a bow, difficult to desribe actually, the noise was quick and sort of "pee-oh" sound. Would anyone know what this is? I thought it might be a nightjar but it's not the same noise as on the RSPB website, so it can't be that. Thank You - Lynne