Security guards at Papua New Guinea's Ramu Nickel Mine have denied access to scientists and medical practitioners investigating a toxic slurry spill in Madang Province.
The Post Courier reports a local and international team of experts engaged by the PNG government were turned away on Friday and Saturday after landing by helicopter at the Basamuk Bay processing site.
The team were told they would face "severe problems" if they did not comply.
Investigators had previously been told, after a meeting with the mining company on Thursday, that they would be allowed to land and take samples.
However, the mining company claimed it agreed to cooperate with an official investigation announced by Prime Minister James Marape which would be led by the deputy PM Davis Steven.
The company has said it refutes claims about the hazards caused by the heavy metals leached from the spill.
However, it appears to be stifling the investigation.
The spill in late August sent 200,000 litres of toxic slurry into the sea on the Rai Coast which led to a fishing ban following the death of a man who'd eaten what locals said was a fish poisoned by the spill.
High levels of nickel, cobalt, magnesium and cadmium caused the death of a dolphin and the surrounding sea to turn red.
But the impact from mine waste on the local marine environment stretches back about seven years, according to an oil spill response consultant from Sweden who investigated the recent event.
Dr Alex Mojon said the mine operator had been releasing millions of litres of toxic waste annually into the sea and expecting it to disappear.