A construction worker in Perth, Western Australia, has been injured on top of a city building which required a large scale emergency response.

Ambulance crews needed to catch a lift 50 metres up an unfinished building to assess the man, while traffic in the CBD was disrupted as adjoining roads near the building were closed in order to carry out the emergency.

The man slipped at a construction site on Murray Street around midday. He is expected to make a full recovery.

Worksafe WA is investigating the incident.