At 7am on Thursday, NSW Ambulance Paramedics responded to reports a 36-year-old man and a 58-year-old man sustained injuries while working on the construction of a new mobile cell site on an apartment building in Burwood.

The 36-year-old man suffered burns to his face, neck, chest and arms, and was in a critical condition at the time while the 58-year-old man suffered burns to his face, neck and hands, and was in a serious condition.

A NSW Ambulance spokesman said both were taken to Concord Hospital as a result of their injuries.

A spokeswoman for Vodafone said that the pair were sub-contractors for the telecommunications company's contractor, HighForce, and the cause of the incident was under investigation.

"SafeWork NSW has taken control of the site and cordoned off the area. We are fully co-operating with SafeWork NSW and assisting with its investigations," the spokeswoman said.

"The safety of our employees, suppliers and the community is our highest priority. We have comprehensive training and strict rules and processes in place to ensure safety is front of mind at all Vodafone sites."

The spokeswoman said Vodafone's thoughts were with the injured men, and that they were providing support to them and their families.

In February 2016, a rigger - subcontracted by Ozziebuild - fell 68 metres to his death after climbing a Telstra communications tower near Darwin.

An inquest into his death found he had climbed the tower without a harness to retrieve tools as a storm approached.

with Jennifer Duke