The maritime union is demanding the release of over a dozen port workers from mandatory quarantine in Darwin.

Thirteen port workers were ordered into quarantine last week after health authorities said they breached personal protective equipment (PPE) protocol while working on the Tacoma Trader container ship that arrived from Singapore.

NT Health says the PPE breaches were observed and reported by Australian Border Force officials, and while no COVID symptoms were reported among the ship's crew, there remains a risk of asymptomatic transmission.

“Although workers did not come into direct contact with any crew members, they did come into contact with surfaces that may be contaminated,” the spokesperson said.

“Failure to wear full PPE puts port workers at risk as well as that of their families and the broader Northern Territory community.”

Assistant national secretary of the Maritime Union of Australia, Adrian Evans, says the workers were initially told that the problem was an error by the ship's agent, and that the forced quarantine was a “bureaucratic overreaction”.

Mr Evans said authorities would not clarify how PPE protocols had been breached.

“Our guys have worked that vessel like they've worked every other vessel since the onset of COVID,” he told the ABC.

“This is no different and we don't know why they've been locked up.”

The union says the ship was cleared for unloading after temperature checks of the crew and a declaration by the master that there were no COVID cases on board.

The maritime union wants rapid COVID tests to be made mandatory for international arrivals at all Australian ports. They say this is especially important for ships coming from Asia to Darwin, as they very rarely spend more than 14 days at sea before arriving.