The cause of mass crab deaths off the North East coast may never be known, an environment minister has claimed amid calls for further investigation.

Mark Spencer told MPs that scientists are “ready to jump into action at great speed” to try to establish the facts if a repeat mass die-off of marine life occurs on the coastline from Hartlepool to Whitby.

Read more: Ben Houchen calls on Thérèse Coffey to support Teesside fishermen

Mr Spencer stressed he hopes a repeat does not happen but added “we may never find the cause” of the original incident between October and December 2021, which saw crustaceans washed ashore and dying creatures “twitching” and displaying lethargic behaviour.

Shadow environment minister Daniel Zeichner suggested the Government is trying to brush the issue “under the carpet” and the Government was 'missing in action'.

Mr Zeichner was speaking in response to a ministerial statement to the House of Commons from the Government about the independent report on deaths of crustaceans and other animals in the North Sea off the Teesside coast since October 2021.

In his prepared words to the House, Mr Spencer repeated - verbatim - the statement sent out by the Secretary of State for the Environment, Therese Coffey, on publication of last week's report.

It isn't clear if there's been any progress in the Government's aim since the report's publication as to whether or not further analysis by the Department for the Environment's (Defra) Centre for Environment, Fisheries and Aquaculture Science (CEFAS) will take place, however Mr Spencer said that CEFAS were "ready to jump into action" if further die-offs were to take place.

A fresh report into the crustacean deaths last week was unable to find a single cause for the mass wash-ups.

The report was unable to identify a “clear and convincing single cause” for the deaths and ruled the chances of dredging on the Tees as being a factor as “exceptionally unlikely”

The Crustacean Mortality Expert Panel (CMEP) also backtracked on a February 2022 report into the wash-ups which said the deaths were due to a “naturally occurring harmful algal bloom.”

Four main factors were considered by the panel, a possible disease, a harmful algal bloom, toxic chemicals including pyridine, and dredging – but all were ruled out as a clear single cause.

Instead, the panel concluded it was “about as likely as not” that a pathogen new to UK waters – a potential disease or parasite – caused the deaths.

Mr Spencer, when asked by Labour MP Kevan Jones (North Durham) about the next steps, told the House of Commons: “It is about taking advice from those scientists and working with them so they can establish the facts of what has caused this disease.

“As much as the House and I want to find the actual cause of this die-off, we have to face the scientific fact that we may never know, if that event doesn’t repeat itself, which I sincerely hope it doesn’t, we may never find the cause of that event.

“But if it is repeated then those scientists are ready to jump into action at great speed to try and establish the facts.”

Mr Zeichner said: “Why is it that 15 months on they still don’t know? Is it because we have a Conservative Government and a Conservative Tees Valley mayor who have been missing in action?

“Is it because they aren’t interested in uncovering the reasons behind it and are more concerned with trying to brush this issue under the carpet?

“Or is it because their priority is protecting a narrow political agenda rather than the interests of the people of Teesside and North Yorkshire? Or is it all of the above?”

He added: “Dither, delay, hard-working people paying. Why is it that the Government has been sitting on committing to, or allowing, further investigation?”

Mr Spencer replied: “I think that is absolutely outrageous, to be honest, to try and play politics with this disaster. And it is a disaster. There is a shared desire across this House to try and find out what caused this die-off. It has been catastrophic to that industry.

“We have had the best scientists in the world looking at that. We are blessed with some of the most expertise in the world in terms of aqua science looking at this.

“And unfortunately the way science works, is it is very difficult sometimes to identify exactly what is the cause. It is of course possible to rule out what it isn’t. And that’s what the expert panel has done.

“The independent panel concluded that pyridine or another toxic pollutant, as a cause, was very unlikely, as was any link to dredging in the freeport. Now they may want to play politics with that, but that does not do those fisherman in the North East any good.”

Darlington Conservative MP Peter Gibson described crustacean die-off as “deeply concerning” and sought assurances about what more the minister considers “reasonable to do before we conclude that we simply do not know what single cause was responsible”.

He also criticised “conspiracy theories and political” mud-slinging from Labour MPs.

Sir Robert Goodwill, Scarborough and Whitby MP, added: “Labour might be entitled to their own opinion but they are not entitled to make up their own facts.”

Stockton North Labour MP Alex Cunningham  said: “As there is still no definitive cause, nothing can be ruled out and only a further in-depth, transparent scientific study will give our communities the answers they deserve.”

Mr Spencer, in his reply, said: “His advice appears to me to be Tinkerbell politics, where we close our eyes and hope we can find the answer, that’s not how it works.”