Marking ball whilst another ball is in motion

[Turtleboy]

I spent over an hour trying to find an answer to this, but find conflicting answers.

Stroke play.
Player A putts from off the green, player B thinks it is going to hit his ball, so he very quickly marks & lifts his ball to prevent collision.
I was under the impression it is not allowed to try & influence the outcome of the shot while the ball is in motion.
Can someone please direct me to the ruling?

 

[2blue]

Will have to leave the exact ruling to others, but I think you'll find it only applies if they are putting on the green.

 

[duncan mackie]

It is now permitted if player B's ball is on the putting green (by the exception to rule 11.3)

 

[2blue]

It is now permitted if player B's ball is on the putting green (by the exception to rule 11.3)

Ah... good... another sensible change in new rules