Boris Johnson could face legal action over a delay to start the Covid inquiry by families who lost loved ones during the pandemic.
Campaigners are concerned that the Prime Minister's failure to set a start date could result in crucial evidence being destroyed.
He committed in Parliament last year to a public inquiry starting in Spring 2022 and appointed retired judge Baroness Hallet to lead it last December.
But more than six months later, the official investigation into the UK's handling of the pandemic, which is expected to be embarrassing for the Government, has still not begun.
Downing Street has yet to announce the final terms of reference for the probe which will cover everything from care home deaths to lockdowns.
Covid-19 Bereaved Families for Justice campaign are now considering taking out a judicial review against ministers.
Elkan Abrahamson, of law firm Broudie Jackson Canter which is advising the campaign said: “In the vast majority of inquiries a setting up date is given within days or weeks of the chair being appointed, so this delay of over six months is both unprecedented and totally inexplicable.
"The consequences are extremely serious, as it only becomes a criminal offence to destroy or tamper with evidence after the inquiry's start date.
"By failing to give one, the Prime Minister is opening the door to key evidence being destroyed.
He added: "After everything they’ve suffered, the last thing bereaved families want is to take legal action against the Government, but if the Prime Minister is going to continue doing all he can to delay the inquiry and undermine its credibility before it’s even begun, they may be left with no choice.”
The campaign says that the 2005 Inquiries Act states that “an inquiry must not begin considering evidence before the setting up date”, meaning the probe remains in limbo.
The families have also raised concerns that it only becomes an offence under the Act to destroy or tamper with evidence after the inquiry has actually been set up.
Jo Goodman, co-founder of Covid-19 Bereaved Families for Justice said: “It’s clear that the only lesson the Prime Minister learned from Partygate is thinking he can get away with lying to the faces of bereaved families.
"He assured us he would begin the inquiry by Spring 2022, a deadline that was already far too late, and here we are at the end of June with no progress.
"These delays slow down how quickly we can learn lessons from the pandemic and could cost lives, so why is the Prime Minister endlessly wasting time?
"He could set the inquiry up and get the process moving with the stroke of a pen."
She added: "Even more worryingly, this delay makes it far more likely that key evidence will be lost or destroyed.
"If the PM can’t do what’s needed to let Baroness Hallet crack on with the job of learning the lessons from the deaths of our loved ones, we’ll need to consider every option available to us."
The pandemic has so far resulted in 196,977 fatalities with Covid on the death certificate.
A Government spokesperson said: “In accordance with the Inquiries Act, the Prime Minister has consulted the devolved administrations and is now finalising the terms of reference. These will be published shortly.”
