Shortly before 1410hrs as part of the student march was passing through Parliament Square a number of protestors climbed barriers onto the pavement around the Square itself and challenged a small group of police officers.
Various missiles were thrown at the officers and protestors pulled down protective fencing around the grass area in Parliament Square.
A large group of protestors walked onto and have occupied the grass area.
The officers withdrew from the area.
Three officers suffered minor injuries.
There have been no arrests at this stage.