Four ministers were warned about tower block fire risks
Four separate government ministers were warned that fire regulations were not keeping people safe, in letters that have subsequently been seen by the BBC.
In the leaked letters, experts warn that those living in tower blocks like Grenfell Tower were "at risk".
At least 79 people are dead or missing presumed dead after the fire at the London high-rise last week.
The department that received the letters said work to improve regulation and safety had already been under way.
The letters show experts have been worried about fire safety in tower blocks for years.
Following a fatal fire in Lakanal House in south London in 2009, a series of recommendations were made to keep people safe.
They were ignored. The government promised a review of fire regulations in 2013, but it still has not happened.
BBC One's Panorama has obtained a dozen letters sent by the All-Party Parliamentary Fire Safety and Rescue Group.
Informed by experts, it warned the government it "could not afford to wait for another tragedy".
Four ministers - all from the Department for Communities and Local Government - received letters but did not strengthen the regulations.
Ronnie King, a former chief fire officer who sits on the group, says the government has ignored repeated warnings about tower block safety.
"We have spent four years saying 'Listen, we have got the evidence, we've provided you with the evidence, there is clear public opinion towards this, you ought to move on this'," said Mr King.
After six people were killed at Lakanal House in 2009, the coroner made a series of safety recommendations for the government to consider.
The government department promised a review in 2013, but it was soon delayed.
In March 2014, the parliamentary group wrote: "Surely… when you already have credible evidence to justify updating… the guidance… which will lead to saving of lives, you don't need to wait another three years in addition to the two already spent since the research findings were updated, in order to take action?
"As there are estimated to be another 4,000 older tower blocks in the UK, without automatic sprinkler protection, can we really afford to wait for another tragedy to occur before we amend this weakness?"
After further correspondence, Liberal Democrat MP Stephen Williams - who was then a minister in the department - replied: "I have neither seen nor heard anything that would suggest that consideration of these specific potential changes is urgent and I am not willing to disrupt the work of this department by asking that these matters are brought forward."
The group replied to say they "were at a loss to understand, how you had concluded that credible and independent evidence, which had life safety implications, was NOT considered to be urgent".
"As a consequence the group wishes to point out to you that should a major fire tragedy, with loss of life, occur between now and 2017 in, for example, a residential care facility or a purpose built block of flats, where the matters which had been raised here, were found to be contributory to the outcome, then the group would be bound to bring this to others' attention."
The letters were written before the refurbishment of Grenfell Tower.
One went to the-then Communities and Local Government Secretary Eric Pickles, who received a letter about fire regulations from the parliamentary group in February 2014.
He had also been asked to look at fire safety in February 2013 and March 2013 by two separate coroners, investigating two tower block fires.
In December 2015, the all-party group wrote to Conservative MP James Wharton, another minister in the department at the time, and warned about the risk of fires spreading on the outside of buildings with cladding.
"Today's buildings have a much higher content of readily available combustible material. Examples are timber and polystyrene mixes in structure, cladding and insulation.
"This fire hazard results in many fires because adequate recommendations to developers simply do not exist. There is little or no requirement to mitigate external fire spread."
The last of the four ministers in the department to receive a letter was Gavin Barwell, who has since moved on to become Theresa May's top aide. He received his letter from the parliamentary group in September last year.
In November, Mr Barwell replied to say his department had been looking at the regulations, and would make a statement "in due course".
In April this year, Mr Barwell wrote to say he did "acknowledge that producing a statement on building regulations has taken longer than I had envisaged".
The fire safety group pointed out that it had been "given a similar response by three successive ministers since 2010" and it "is now time to listen to what the Fire Sector is saying".
The government has said there is still no timetable for a review.
The Department for Communities and Local Government said that a police investigation into the Grenfell Fire is already under way "but it will be some time before it is fully understood how the fire started or why it took hold in the way it did."
In a statement, it added: "The government has acted to improve fire regulation and safety, including the recommendations made by the Coroner following the Lakanal House Fire.
"The final recommendation concerned simplification of fire safety guidance, and this work was under way, with a consultation due to be published this summer.
"Fire safety requirements are complex issues and our priority has been that we have high standards. A great deal of work has been completed, including commissioning and undertaking research to support the planned consultation. Clearly, in light of this tragic event, we need to reflect on whether this consultation is the correct next step to take. We will confirm our approach shortly."
In a separate development, Panorama has discovered that firefighters put out the first fire at Grenfell Tower.
They were called to a fridge fire, and within minutes told residents the fire was out in the flat.
The crew was leaving the building when firefighters outside spotted flames rising up the side of the building.
The Fire Brigades Union say firefighters were left facing an unprecedented fire, and officers broke their own safety protocol to rescue people.
Watch Panorama - London Tower Fire: Britain's Shame on Monday 19 June at 20:30 BST on BBC One and afterwards on BBC iPlayer.