Australia’s second largest port operator told a Senate inquiry into workplace laws on Monday the dispute was leading to a backlog of more than 54,000 shipping containers as well as an $84 million weekly hit to the economy.

DP World vice-president Mark Ratcliffe said new laws allowing for multi-employer bargaining would lead to other port operators facing similar strikes.

“We are concerned that it could cripple all ports. All the other major port and terminal operators have their enterprise agreements expiring … between March of this year and December of next year,” he told the inquiry.

“If we ended up in a situation of multi-employer bargaining, once those enterprise agreement expire, then essentially the protected industrial action that we’re seeing now could go across the entire ports and terminal operators of the country.”

Unions have called for a 16 per cent pay rise for DP World staff to bring salaries into line with fellow stevedore Patrick.

However, DP World’s head of corporate affairs Blake Tierney said its port workers were still highly paid.

“Our employees are paid in the top 10 per cent of earners in Australia,” he said.

“We appreciate our employees are specialised and unique. However, we require productivity in our ports to make sure they are resilient, modernised and efficient.”

Workplace Minister Tony Burke said the government would not intervene in the industrial dispute, despite calls for it to happen.

But Mr Tierney said workplace laws before federal parliament were inconsistent with the bargaining process.

“We suggest structured dialogue for dispute resolution, and caution against minimum, standard orders in limiting flexibility,” he said.

It comes as the Business Council of Australia warn the industrial relations laws would bring “self-inflicted damage” to the economy.

The laws would bring an end to labour hire loopholes and create pathways for casual staff to become permanent.

But the council’s chief executive Bran Black said the laws on casuals would be a deterrent for employers.

“(The new law) is going to make offering casual jobs far less appealing for employers, and finding those kinds of jobs harder for employees,” he said in an opinion piece.

“It’s difficult to overstate the importance of casual jobs to our economy, they make up almost a quarter of all jobs.”

Debate on the industrial relations laws is set to resume in federal parliament in February when MPs and senators return to Canberra.