* Grenfell Tower fire killed 71 people in June 2017
* Inquiry says combustible cladding played major role
* Safety warnings from community were ignored before fire
* PM Johnson says will act on inquiry's recommendations (Adds quotes from survivors' group, PM Johnson, other details)
By Estelle Shirbon
LONDON, Oct 30 (Reuters) - Combustible materials used to refurbish London's Grenfell Tower were central to the catastrophic chain of events in June 2017 that turned an ordinary kitchen fire into an inferno that killed 71 people, an official inquiry said on Wednesday.
The blaze at Grenfell Tower, a 23-storey social housing block owned by one of London's richest local authorities, shocked Britain and threw up a range of disturbing questions about how the building had been allowed to become a tinderbox.
"Grenfell Tower was home to a strong and vibrant community that was torn apart by the fire," said inquiry chairman Martin Moore-Bick in an introduction to his report on Phase 1 of the inquiry, which focused on events on the night of the blaze.
Having started in a fourth-floor flat due to an electrical fault in a refrigerator, the fire spread to the outside of the building and set it ablaze, racing up to the roof in less than half an hour and quickly engulfing the entire building.
The speed with which the flames spread was due to the fact that the tower's external walls had been fitted during a refurbishment completed in 2016 with a combustible cladding and insulation system that acted as fuel, Moore-Bick said.
He said there was compelling evidence the cladding did not comply with regulations.
Grenfell United, a group representing survivors and bereaved families, said the Kensington and Chelsea local authority, which owned the building, and the companies involved in the refurbishment, had questions to answer.
"This finding adds to our determination to see criminal charges brought against those responsible for turning our homes into a death trap," the group said in a statement.
A criminal investigation into the disaster is ongoing, but police have said no decision on charges will be made until the public inquiry process has concluded.
Phase 2 of the inquiry, expected to last about two years, will seek to establish how, why and by whom the decision to install the flammable cladding system was made.
In the House of Commons, Prime Minister Boris Johnson and Members of Parliament marked the publication of the Phase 1 report with a minute's silence.
Johnson said there was a need for "a change in our approach to fire safety and indeed to social housing more widely", pledging to implement a series of recommendations made by Moore-Bick to improve many aspects of fire safety rules.
"We must expose and fix the failings that allowed an otherwise safe building to become so dangerous," Johnson said.
Many buildings across Britain are still covered with cladding similar to that used at Grenfell.
Johnson said work to remove dangerous cladding from high-rise blocks had been completed or was scheduled in all government-owned buildings but progress was slower in the private sector. He said the government would release an extra 600 million pounds ($772 million) to go towards the removal of risky cladding.
Located in the wealthy area of Kensington, Grenfell Tower was home to a close-knit community that traced its roots to places as diverse as Britain, Afghanistan, Lebanon, Morocco, Gambia, Ethiopia, Italy and Trinidad.
The report paid tribute to the 71 people who died on the night – 70 adults and children who were unable to escape the tower, and one baby who was delivered stillborn after his eight-month-pregnant mother was evacuated through toxic fumes.
Critics have accused the local authority of neglecting the tower because of indifference towards its low-income, immigrant residents - prompting a wider public debate about Britain's yawning rich-poor divide and class prejudice among officials.
Moore-Bick alluded to this context in his report, saying that Phase 2 of the inquiry would examine the issue of why warnings by the local community before the fire that Grenfell Tower was unsafe were ignored.
"There is a strong feeling among them that their voices were ignored and that if attention had been paid to them the disaster could have been avoided," he wrote.
Johnson acknowledged the Grenfell community had been "too often overlooked and ignored in the months and years before the tragedy, and, shamefully, failed by the institutions that were supposed to serve them in the days and weeks after it." (Editing by Stephen Addison)
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