Casual warehouse workers at Caterpillar in Melbourne have been threatened with the sack if they apply for permanent jobs.

Their Agreement with Caterpillar has provisions for casual workers to be made permanent after nine months of work.

But The Age and the Wall Street Journal have reported that casual workers were forced to sign letters saying they did not want permanent jobs.

Casual workers at Caterpillar should not be threatened with the sack for accessing their legal entitlements.

It's time Caterpillar stopped bullying its casual workers and respected their right to secure jobs.