Picket lines at distribution centres amount to a “gun to the head” for Woolworths and fly in the face of good-faith bargaining, the supermarket’s lawyers have told the workplace umpire.

A Fair Work Commission hearing began on Friday on Woolworths’ application to stop United Workers Union members picketing at four key distribution centres in Victoria and NSW.

The major supermarket closed the centres because it did not have enough staff to operate them safely. It has repeatedly claimed that staff who want to go back to work have been blocked by union members.

The union has labelled the hearing a distraction and called for Woolworths to show its workers “dignity and respect”.

Sixteen days of industrial action has left thousands of supermarket and bottle shop shelves empty in Victoria, NSW and the ACT and cost Woolworths at least $50 million.

Woolworths lawyer Marc Felman said the distribution centres were the “heartbeat” of its ability to get products to Australians as he argued the picketing amounted to unfair conduct in their bargaining.

“They should be free to continue to come to an agreement in an orthodox way without the gun to the head of an obstructive picket,” Felman told the hearing in Melbourne.

Outside of the commission hearing, United Workers Union secretary Tim Kennedy said members wanted better pay and changes to a computerised performance management framework that put workers at risk.

“Woolworths can step forward and show some dignity and respect to their workers … so they can plan for Christmas,” he said.

The union said Woolworths had insisted on holding separate talks at each of the four affected warehouses, stifling the bargaining process.

But the retail giant’s lawyers claimed there had been picketing at warehouses not involved in talks.

Kennedy said negotiations were ongoing and narrowing-in on issues, and the Fair Work hearing amounted to a distraction.

“Woolworths made the decision on the 21st of November to shut all their warehouses. The orders they’re seeking today is to open their warehouses,” he said.

“I think the problem is that Woolworths are used to just saying ‘it’s our way or the highway’, whether that’s to farmers, suppliers or customers.”

Woolworths said the obstructive pickets undermined the bargaining process and was therefore not protected action under Australian law.

“You are able to peacefully protest and take protected strike action,” Felman told the commission hearing.

“What you can’t do is be obstructive about it.”

Two witnesses for Woolworths and its distribution arm Primary Connect gave evidence to the hearing, but no union representatives gave verbal evidence, opting to tender documents instead.

The hearing continues.

-AAP