The Enquirer understands the departures include heads of the rail division and investment arm.
One company source said: “A number of high-profile people within the firm have now gone with others also let go in the next rank down.
“It looks like others could go and feels like a reinforcing of the ‘old guard’ at the company.”
Departures include Lisa Scenna, managing director of the Explore Investments Group, Paul Copeland head of rail, Duncan Symonds ,director infrastructure, Lee Marks, commercial director and David Hills construction director.
An O’Rourke spokesman said: “This is a handful of changes at a company of our size and is not any sort of restructuring.
“A number of senior staff have joined recently and a number have left – that’s the nature of a company the size of Laing O’Rourke.”