Toyota's Daihatsu unit will halt shipments of all of its vehicles, Japan's biggest automaker said Wednesday, after an investigation into a safety scandal found issues with 64 models, including almost two dozen sold under the Toyota brand.

An independent panel has been investigating Daihatsu after it said in April it had rigged side-collision safety tests carried out for 88,000 small cars, most of those sold as Toyotas.

But the latest revelations suggest that the scope of the scandal is now far greater than previously thought, and could potentially tarnish the automakers' reputation for quality and safety.