French investigators found jihadist propaganda material on Saturday in the computer of a man who drove his car into troops guarding a mosque in France on New Year's Day but said it did not prove he had links with any terrorist groups.

"The inspection of his computer led to the discovery of jihadi propaganda images," local prosecutor Alex Perrin told Reuters.

"These are downloadable images that are a few weeks old. Not the worst type of images, but rather bellicose slogans," he said. "It shows he had an appreciation of that but it does not prove he had links with terrorist organizations."