Corporate witnesses involved in refurbishing Grenfell Tower with flammable materials are trying to derail the public inquiry by threatening to stay silent unless they are guaranteed they will not be prosecuted, it has been claimed.

The inquiry into the disaster which killed 72 people heard that the "potential perpetrators of this inferno" are trying to "essentially dictate the terms in which they will provide their assistance".

Chairman Sir Martin Moore-Bick is considering a request to write to Attorney General Geoffrey Cox QC asking for an undertaking that would stop any evidence staff may give being used against them in any future criminal proceedings.

Representing victims, Michael Mansfield QC said on Monday that there is an "overwhelming and strong" consensus opposing the application.

The families say to them directly today, would they kindly take a moment to reflect and reconsider whether they really want to put the families through more anguish, more agony through the months that come. They are pretending that they want a full and open inquiry in which they will co-operate. We say it is abhorrent to the interests of justice that those who are potential perpetrators of this inferno, who have caused the loss of life, injury, which is often overlooked, the loss of homes. Then, and continuing now and well into the future, can those potential perpetrators come here and essentially dictate the terms in which they will provide their assistance?

Michael Mansfield QC
Michael Mansfield QC at the Grenfell Tower public inquiry Credit: PA

Mr Mansfield said the timing of the application appears to be an "attempt to derail this inquiry", adding: "If it was serious this would have been done months ago."

Going one stage further, I would say were it to be granted, given the climate of denial and buck-passing ... the granting of an undertaking in this context will be tantamount, I fear, to a licence to lie.

Michael Mansfield QC

But Sir Martin said that "might be going a bit far" as it would not cover giving false evidence to the inquiry.

Stephanie Barwise QC added:

In short, the timing of this application is highly disingenuous and bears all the hallmarks of sabotage of this inquiry.

Stephanie Barwise QC

Retired appeal court judge Sir Martin is hearing the application for firms including external wall subcontractor Harley Facades, main contractor Rydon, architects Studio E, and window and cladding fitters Osborne Berry.

The collective application sent to him said the pledge would "fulfil the inquiry's primary obligation ... in the most effective and least disruptive manner".