About 2,000 union members have marched through the city to the Premier Colin Barnett's office demanding manufacturing and engineering jobs for resource projects remain in Australia.

The communications electrical and plumbing union have been joined by the MUA, CFMEU and AMWU members, who are holding flags and chanting.

The unions say too much steel fabrication is being done offshore, meaning less jobs for Australians, while youth unemployment continues to rise.

They are hoping for an election commitment that projects be offered to Australian companies before being sent overseas.

The Commerce Minister Simon O'Brien admits it is a challenging time for the steel industry, but insists the Government's local content policy is working.

"We are achieving 80 to 90 per cent local content levels on onshore projects and over 50 per cent of offshore projects," he said.

Mr O'Brien says West Australians have excellent employment opportunities.

"We've seen over $34 billion in resource projects flow into local companies and that's resulted in over 70,000 jobs," he said.

"We've got the lowest unemployment rate of any state in Australia. So if you're looking for a job, this state is the best place in the world to be.

However, the Opposition says it will legislate to create local jobs if it wins the State election.

Labor MP Fran Logan told the crowd his party is the only one with a plan to secure local jobs.

"We'll ensure on Government contracts that contractors are required to employ apprentices," he said.

"We spend a lot of money on building infrastructure. That money has to be used properly and used to employ the tradespeople of the future and we'll do that as a Government."