An escalating industrial dispute between maritime unions and Australia's main tug boat operator threatens to disrupt Christmas supply chains, and cause havoc on ports across the country.

Danish tug boat giant Svitzer will lock out 582 employees from 17 ports indefinitely, in response to what it described as "damaging" industrial action.

The company holds a near monopoly over hauling operations in key ports, and has been locked in enterprise agreement negotiations with unions for three years.

The company said the union action has resulted in 250 instances of industrial action since late October, amounting to 2,000 hours of work stoppages.

"We had hoped it would never come to a lockout," Svitzer Australia managing director Nicolaj Noes said.

"But we are at a point where we see no other option but to respond to the damaging industrial action underway by the unions."

Mr Noes said he was hopeful the dispute could be resolved before Friday's lockout, which he said would cause widespread disruption to the freight industry.

"We're such a key part of logistics in Australia so that if we don't work, the ports don't work," he said.

Maritime Union of Australia secretary Paddy Crumlin said the company was acting in bad faith.

"Now they've decided to take a militant national action of shutting down the country's ports because I guess they're big and powerful, they're heading for a $30 billion profit this year, and I guess size doesn't give you much moral energy," he said.