Particles - animated image textures with random time offset...?

I am trying to create a large crowd of people with particle system but have ran into a problem. I have image sequences for different people with simple movement (basically just standing). I created a number of planes and assigned materials and textures to them, then grouped the planes and used this group as particle render type (with “pick random” and “use count”) to create a crowd of 1000 people. All going well.

Now the question:
Is it possible to set random time offset for animated textures on particles?

At the moment it seems that texture animation is running in scene time not particle time and thus all the x copies of one person move at the same time even if I they are created in different times.