Workers are rallying against NT WorkSafe after a spate of accidents including the death of a sailor last month.

A 37-year-old man died after falling from a in Darwin in early January while working with Top End company Barge Express.

Maritime Union spokesperson Thomas Mayor says NT WorkSafe's is failing to investigate properly or prosecute employers.

“The death was at Hudson Creek, a place that we've raised concern with NT WorkSafe in the past and the same place where an employer was dishonest to NT WorkSafe when they didn't act, and now we have a death there,” he told the ABC.

“We think that if NT WorkSafe had acted, this death would not have happened.”

The Maritime Union says the infrastructure used at the Hudson Creek Wharf has been unsafe since part of it collapsed in 2014.

An NT WorkSafe spokesperson said the death is being investigated.

“The coroner's office is also currently investigating this incident,” the spokesperson said.

The unions also claim NT WorkSafe ignored asbestos in demountable housing in Tennant Creek after making an initial visit to the site in November last year.

“NT WorkSafe claims they've been there but how does this asbestos remain in that community, floating around, broken boards of asbestos in these demountable housing and yet the regulator doesn't pick that up,” Mr Mayor said.

The unions say NT WorkSafe has spoken only to employers, not workers.

The NT WorkSafe spokeperson told reporters that workplace safety inspectors were speaking to workers, health and safety representatives, and management, as they are required to do.