How to reduce motion blur artifacts

Hi,

I’m having some issues with the motion blur of our game. It is creating some weird sharp dither-like artifacts that are really noticeable in large screens. The stronger the effect, the worst the artifacts.

Here is a screenshot showing the issue:

268678-motionblur1.png

Detail:

268679-motionblur2.png

Another scene showing the issue even more clearly:

Can you help me solve this issue? What causes this?

Thank you!