The Transport Workers Union (TWU) says Coles truck drivers are involved in illegal practices to meet the unfair pressures of the supermarket giant.

The TWU logged the practices of three companies at the Coles Distribution Centre at Eastern Creek in Sydney, between July 2014and April 2015.

The union says all three transport companies — Northline, Lindsay Transport, and Parry Logistics — broke the rules.

“We found around 126 breaches from a very small sample,” TWU NSW secretary Michael Aird told reporters.

“We believe that's entirely consistent across the Coles supply chain across the country.

“There are thousands of truck movements week in week out in the Coles supply chain that is being performed in an unsafe manner and in an unlawful manner, and it's those practices that directly lead to deaths and injuries on our roads.”

He says the blame rests with the supermarket putting too much pressure on its supply chain.

Issues that the union says Coles causes include drivers skipping rest breaks, cutting them short, or using their rest breaks to load or unload.

The hand-written results of the audit have been given to police and appropriate regulators, with the names of drivers redacted.

The NSW Roads and Maritime Service is reportedly investigating the matter.

The TWU says it may allow a temporary amnesty period for drivers to come forward and report breaches.