A CRASH on a busy road is causing heavy traffic on junction exiting the M4.

Thames Valley Police and South Central Ambulance Service are on the scene after a crash on the A33 Southbound near Three Mile Cross.

A passerby has reported seeing “police sweeping the road” after a crash on the road that leads off the M4 at junction 11.

According to AA live traffic updates, there is heavy traffic in the area with “increasing” delays.

There is an average speed of 10mph.