A former union organiser has been fined $1000 in a Perth court after pushing his chest against a public official who was investigating a strike at a hospital building site.

Former Construction, Forestry, Mining and Energy Union (CFMEU) organiser Matthew Balde was fined in Perth Magistrates Court after pleading guilty to obstructing a Commonwealth public official.

In July 2013, two Fair Work Building and Construction (FWBC) investigators visited the $1.2 billion Perth Children’s Hospital project site to investigate alleged industrial action.

Construction workers had gathered at a park near the site where several CFMEU officials were standing on the back of a utility addressing the crowd with a loud speaker.

Several people in the crowd were also waving CFMEU flags, FWBC said.

The government officials were standing in a nearby public car park when Balde approached one of them and asked what he was doing.

Balde was standing so close to the government official that his chest was touching him and continued to obstruct the official from doing his job even after he was warned, FWBC said.

The official was in clear view of the workers and was filming the group to gather evidence of possible unlawful activity.

A police officer approached and repeatedly told Balde to step away from the official, but Balde refused.

FWBC director Nigel Hadgkiss said behaviour like this was appalling.

“It is absolutely disgraceful that government officials are subjected to this kind of behaviour in the course of going about their job,” he said.

“Unfortunately this is not uncommon and we have several similar matters currently with police.”

FWBC has launched four other court proceedings related to alleged unlawful conduct at the Perth Children’s Hospital site.