Experts warned the government two years before the Grenfell Tower disaster that not enough was being done to tackle the risk of fire spreading through such buildings and that lives were in danger as a result.

Whitehall-commissioned studies produced in March 2015 warned of potential fatalities unless officials addressed the danger of flames passing through concealed cavities. Officials kept the advice confidential. Experts believe that the same process in the cladding at Grenfell helped spread the June 2017 fire, which claimed 72 lives, including 18 children.

Studies by fire experts at the Building Research Establishment (BRE) were blunt in their assessment that fire barriers installed in the wall cavities of some buildings were not performing effectively and that builders needed education on the dangers of getting things wrong.

One of the studies presented to officials at the building regulations division at the then Department for Communities and Local Ggovernment said barriers intended to stop fires spreading were “often found to be missing or incomplete or incorrectly positioned”, which is what emerged later from investigations into the refurbishment of Grenfell on behalf of the public inquiry into the disaster.

Another study warned that people had died because of fire or smoke spread in concealed spaces and “the potential risks and the potential losses remain high”. Inquiry investigations have also found that cavities and vertical channels in Grenfell’s new cladding system were probable contributors to the rapid vertical fire spread.

The reports were placed on the website of the housing ministry on Friday. They sparked anger from Grenfell United, which represents survivors and bereaved families. The group said the reports showed “people and organisations that were meant to keep us safe knew the dangers and didn’t care enough about our lives and the lives of our loved ones to act”.

“The scale of complacency is numbing,” said a spokesperson for the group. “It is deeply concerning that the government has held back information like this for over 18 months since the fire. This is vital safety information that needed to be in the public domain but seemingly was ignored or suppressed for convenience.”

The Ministry of Housing, Communities and Local Government (MHCLG) said the reports were being released now to inform a review of fire regulations for buildings.

The studies reflected industry-wide concern in 2015 that construction methods were posing new fire risks not just confined to the way Grenfell was reclad. They referred to 20 fires between 2003 and 2013 that involved inadequate, missing or badly fitted cavity barriers.

In the 19 months since the fire, 437 residential buildings and publicly-owned buildings over 18 metres have been identified with Grenfell-style cladding systems that the government says do not meet building regulations and must be removed.

The BRE experts urged the government to consider new building regulations guidance and new ways for building inspectors to check works were safe, but neither move was undertaken.

Their reports were submitted in the middle of the Grenfell refurbishment, but were treated as “commercial in confidence” and so were not made public.

One study said that “poor workmanship with inappropriate materials are the main reasons for the inadequate protection of concealed spaces”. It said: “Whilst these concerns have not been disputed by manufacturers there are no drivers to encourage more effective solutions to be developed.” It warned that “inadequacies cannot be seen by the building users and will not be apparent during everyday use” and “will only become apparent during a fire”.

Building inspectors working for the Royal Borough of Kensington and Chelsea approved the £10m Grenfell refurbishment after making 16 site visits.

Grenfell United said it now expects all the officials involved in the report to be questioned in the public inquiry.

“We fully expect to see BRE and government officials explaining why dangers were known but action wasn’t taken, despite years of warning,” it said.

The studies were produced as part of a plan to update building regulations, but government officials conceded this took longer than planned and remained ongoing four years later.

“Our technical review will address the issues raised in the reports and our overall plan for stronger, tougher rules on building safety will create a more rigorous system that delivers meaningful and lasting change,” said a spokesman for the MHCLG.

The emergence of the warnings will also raise questions about whether the London fire brigade and RBKC should have known more about the risks at Grenfell. The reports were overseen by a steering group of 23 organisations which included the Chief Fire Officers Association and LABC, which represents all local authority building control teams in England and Wales.

Dany Cotton, the commissioner of the London Fire Brigade and a member of the National Fire Chiefs Council, repeatedly told the public inquiry in September that it would have been impossible to prepare her staff for the fire because the way the building behaved was so unexpected, saying: “I wouldn’t develop a training package for a space shuttle landing on the Shard.”

A London Fire Brigade spokesperson said compartmentation failure was just one line of enquiry being examined by the inquiry.

“We have recently highlighted a lack of fire safety competence and expertise within the construction industry and have called for loopholes which allow technical fire safety elements to be designed without the involvement of a competent fire safety professional to be closed,” they said.

The BRE said it had communicated the findings of the reports to industry audiences before and after Grenfell.

“Life safety is our key priority,” a spokesperson said.