Fishing Minister Victoria Prentis has said "we may never know for sure" what caused the freak death of thousands of crustaceans on the North East coast.
Her comments would appear to undermine a report by Government scientists, which concluded earlier this year that a strange algal bloom was to blame.
Independent marine pollution experts have argued the cause is linked to a specific chemical called pyridine - quantities of which were found to be more than 70 times higher in some crab samples taken from Saltburn and Seaton.
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Ms Prentis, speaking in a Westminster Hall debate, said a wider review of all the evidence was being conducted and was due to report in March next year.
The comments however will provide little comfort to fishermen in the North East who face "ruin", according to one MP.
Stockton North MP Alex Cunningham said coastal areas that used to be full of wildlife are "now desolate", adding: "While the destruction of marine life is already devastating from an environmental perspective, the impact that it is having on the fishing industry in the North East could be terminal.
"In the first die off in October, the local fishing industry reported a 95% decline in the lobster and crab catch. The picture is truly catastrophic.
He added: "It's not good enough for this government to sit back and let this fishing industry die.
"The Government cannot level up our country if it turns a blind eye and simply allows the industries and communities like ours to die away."
Mr Cunningham also argued that there was "too much uninvestigated evidence" and called for a fresh independent inquiry on the cause of the incident.
He said it could not be right that fishermen on his patch had been "left crowdfunding for independent reports to be carried out because we cannot get the government to answer the questions".
Ms Prentis acknowledged the "significant impact on both the local community and the fishing industry" and said monitoring of algal bloom continued in the area.
But in comments that could add to calls for a fresh inquiry, she concluded: "While we concluded that the most likely cause was the harmful algal bloom. We may never know for sure what caused this event."
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