Crane hanging 'precariously' from 51st floor of Barangaroo tower

A crane is hanging precariously from the 51st floor of the highest tower at Barangaroo in Sydney's CBD after it is believed to have been damaged while lowering machinery.

An exclusion zone has been formed at the bottom of Tower One at the northern end of the building project, but there are no reports of injuries in the incident which occurred at about 2pm on Tuesday.

The crane dangles on top of Tower One at Barangaroo in Sydney's CBD. Photo: Supplied

The 3.9-tonne spider boom crane involved in the incident was bolted onto the top of Tower One.

Police are helping with traffic management on Hickson Road, which runs alongside Barangaroo and has been closed to pedestrians.

The Barangaroo towers taking shape. Photo: Peter Rae

A spokesman for the Construction, Forestry, Mining and Energy Union, which represents workers at the site, said the crane was "hanging precariously" from the top of Tower One.

"They were lowering pieces of machinery and it has sort of collapsed under that load," he said. "As to the cause, it is hard to tell at the moment. It is up 51 floors."

Lend Lease, the developer of Barangaroo, said in a statement that there had been an incident "impeding the operation of a crane at Barangaroo".

"We have secured the crane and as a precaution have created an exclusion zone and evacuated people on that part of the project," it said.

"Safety remains our number one priority and engineers are assessing the crane and will advise next steps in due course."

Construction of Tower One, which is now one of Sydney's tallest buildings, is close to completion.

However, it will eventually be overtaken by Crown's casino and hotel complex, which will be built just north of it at Barangaroo.