CFMMEU officials injured after alleged assault at Hawthorn East site

A union official has been rushed to hospital unconscious after he and a colleague were allegedly attacked at a construction site in Melbourne's inner east.

Police are investigating after two officials from the CFMMEU were allegedly assaulted after turning up to a Hawthorn East worksite on Toorak Road just before 7.30am.

One of the men was taken to The Alfred hospital with non-life-threatening injuries to his upper body. He was released from hospital about midday.

The other man did not need to go to hospital.

A spokeswoman for the CFMMEU said two officials had arrived on site with "all their paperwork in order" when they were "attacked and jumped" by up to seven men.

She said one of the officials was knocked unconscious when allegedly struck on the back of the head with some kind of object, believed to be a piece of wood, before being kicked while on the ground.

He was taken to hospital and woke up several hours later but was "not in great shape", she said.

The investigation is now in the hands of police.

Police remained at the site after the alleged assault as a number of colleagues of the two CFMMEU officials turned up at the scene.

Officers stayed there to "ensure public order and that there was no breach of the peace", police said.

They helped to escort workers off the site and by 4pm, a police spokeswoman said, all parties had dispersed.

Toorak Road was closed in both directions between Auburn Road and Tooronga Road due to the incident but reopened late in the afternoon. VicRoads had urged motorists to allow extra time when travelling in the area.

Anyone with information is urged to call Crime Stoppers on 1800 333 000.