Dump trucks, police and council workers have moved into Martin Place, in the centre of Sydney city, to evict dozens of homeless people who have been living there.

At one stage 60 people lived in the camp under the former Westpac building and opposite the Reserve Bank of Australia.

Council workers are clearing out the makeshift camp area where the homeless have been sleeping for months and had set up infrastructure like a 24-hour kitchen.

Council trucks moving in to dismantle the homeless campsite in Martin Place. ( ABC News: Billy Cooper )

Early this morning, before the workers moved in, a City of Sydney representative walked through handing out a letter to the homeless describing the camp as a "public nuisance".

"The accumulation of items in Martin Place, including a barbecue, gas bottles, tents, food and other items has been determined to be a public nuisance as it materially affects the reasonable comfort and convenience of other users of Martin Place," said the letter, written by David Riordan, director of city operations.

The letter includes instructions for collection of any items removed and contacts for homeless services.

A 24-hour street kitchen was set up for the homeless in Martin Place. ( ABC News: Lucy McNally )

A volunteer who represents the group, Lanz Priestley, said the dismantling of the camp would not stop the community setting up elsewhere.

"We're talking to a few parties as to where this might be relocated to. We've got no intention of letting this community down," Mr Priestley said.

"You know this problem is actually the responsibility of the collective governments including council, state and federal."

Homeless sleeping under Lendlease roof

In contrast to the letter they handed to the homeless, the City of Sydney press statement said the homeless camp was setup under the hoardings around a Lendlease Building site.

"The 60 Martin Place hoarding is not a safe or sustainable housing option for people sleeping rough. Alternative accommodation has been offered to all people in the area. Some people have accepted the offer, while others have declined assistance," the statement said.

"The city has repeatedly advised that the barbecue and cooking facilities, and obstruction of a public thoroughfare with large and unauthorised items, presents a significant fire and safety risk.

"There are multiple organisations and charities already operating in the local area providing food to people experiencing homelessness. There is no shortage of food suppliers to support people sleeping rough."

Lendlease workers enclosed the hoarding after the camp had been removed.

Lendlease also had a representative in Martin Place but he did not talk to the group, and shook his head as a protester yelled "Lendlease doesn't care about safety — look what happened at Barangaroo!"

Camp moves close by

Homeless people packing up to leave Martin Place after being evicted by the council in the early hours. ( ABC News: Lucy McNally )

After waiting for some tension to die down, the council workers began packing up milk crates and picking up rubbish from the area.

Some of the homeless woke early to pack up their belongings, but most of them have not taken them far; they moved them to the other side of Martin Place, directly under the Reserve Bank.

There is now a similar makeshift camp there, with blow up mattresses, beds and bags of clothes sitting on the walkway.

But unlike their previous camp, this one has no roof, so the group will be more exposed to the cold winter weather if they choose to sleep there tonight.