A group of about 50 protesters, some chained to trees, had to be removed by police to allow construction crews to begin preparation work for the Sydney light-rail project.

At least six people chained themselves to the mature trees lining Alison Road and Anzac Parade in Randwick before construction workers arrived about 8:00pm on Thursday.

Their protest was preventing crews from clearing the site and beginning work.

The group had come together in a last-ditch effort to save the trees, some more than 100 years old, from the new $2.1 billion light-rail project.

They claim the State Government backtracked on the initial route for the light rail, which was supposed to run on the south side of the road, in front of Randwick Racecourse.

Protesters devastated by loss of trees

Local Claire Steigrad said the New South Wales Government had been ignoring their pleas.

"People are really angry that this is happening. People have been saying for over a year that we don't want these trees cut down and nobody is listening," she said.

"To the people of Sydney I say, you are losing 50 heritage trees so the racecourse can keep a bus lane and 150 car spaces."

Early on Friday morning tree mulching trucks made their way through the security gates on the corner of Alison and Darley roads.

Protester Eryl Brady believed it was appalling the trees were cut down. ( ABC News: Mark Reddie )

Construction workers left shortly after, but security guards and police continued to secure the area.

Angry local residents watched today as more trees were cut down, including Eryl Brady, 77.

"I don't want a tram, it's too late for that but if there is a tram I don't want it coming through Centennial Park. I don't want trees cut down or pruned.

"I came along because I knew they were going to cut today and I was determined to come and make my own protest."

Jayne Leadbetter, 54, returned to the site after chaining herself to one of the trees overnight.

"I was with a group of people who are really saddened about the loss of these 160-year-old trees and the habitat for bird life and animal life in the local area," she said.

"We had a peaceful sit-in to indicate how devastated we are by the loss of these beautiful trees.

"The police told us that we were on a construction site and as it's fenced off we had to leave the area, which we did eventually."

Government to plant more trees

Transport NSW has stood firmly by their decision, assuring residents that it would plant significantly more trees than it removed.

A spokesman for the NSW Minister for Transport and Infrastructure said the ALTRAC Light Rail consortium has confirmed it intends to remove approximately 50 trees depending on weather conditions, with work scheduled from January 7-16.

He said the goal was to retain as many trees as possible throughout the project and that more trees would be planted than the number removed, including mature trees.