Commuters in Sydney's south east have been warned to expect major disruptions to their daily travel into and out of the CBD as construction ramps up on the $2.1 billion light rail project.

Work will start on Saturday on a stretch of Anzac Parade – a key arterial route – between Todman Avenue and High Street, near the University of NSW.

Transport Minister Andrew Constance said the disruption from construction would make "life very difficult" for people in Sydney's south east for the next two years.

"We are sending a very clear message to those residents throughout the south east – please plan your trips," he said.