Witnesses at the Grenfell Tower public inquiry will be allowed to give evidence without incriminating themselves, the attorney general has announced.

Suella Braverman said staff of companies and organisations involved in the disastrous refurbishment would be able to give oral evidence about how the tower was clad with combustible materials, without it being used against them in any future criminal prosecutions. The undertaking will not protect corporate entities, as some of the lawyers had requested.

Detectives are investigating possible crimes ranging from breaches of the Health and Safety Act to manslaughter in relation to the 14 June 2017 disaster at the west London council block which killed 72 people.

Survivors and the bereaved said the decision made them “nervous”.

“We can’t help but worry about how this will impact prosecutions later,” said a spokesperson of Grenfell United, the community group. “It is clear that corporate lawyers are playing every trick in the book.”

Timeline Key events since the Grenfell Tower fire Show Hide

The fire breaks out in the early hours of the morning, prompting a huge response from emergency services, who are unable to bring the fire under control or prevent a severe loss of life. The then Conservative prime minister, Theresa May, visits the scene and orders a full inquiry into the disaster, and the government promises that every family will be rehoused locally. The communities secretary, Sajid Javid, orders an emergency fire safety review of 4,000 tower blocks across Britain, and it will emerge that 120 tower blocks have combustible cladding. Scotland Yard launches a criminal investigation into the Grenfell fire. The chancellor, Philip Hammond, says the cladding used on Grenfell Tower was banned in the UK. The retired judge Sir Martin Moore-Bick is appointed to lead the public inquiry. Kensington and Chelsea council’s first meeting since the disaster is abandoned after the council fails in a bid to ban the media from attending. Survivors have their first official meeting with the police and coroner. The inquiry formally opens. As the final death toll is confirmed to be 71 people, it is revealed that hundreds of households are still living in hotels. In defensive testimony at the inquiry, London fire brigade commissioner Dany Cotton said she would not change anything about the way the brigade responded to the Grenfell disaster, provoking anger from both survivors and the bereaved. Grenfell survivors and the bereaved expressed frustration at Scotland Yard after they admitted no charges were likely until 2021. The public inquiry report concludes that fewer people would have died had the fire brigade been better prepared. Leader of the House of Commons Jacob Rees-Mogg is forced to apologise after stating that victims of Grenfell did not use "common sense" and leave the burning building. Grenfell cladding firm Arconic reveals it has spent £30 million on lawyers and advisors defending their role in the disaster. The second phase of the Grenfell Tower inquiry begins. Stacee Smith and Grace Mainwaring

The second phase of the inquiry, investigating the refurbishment works, was halted on 4 February by a demand for assurances evidence would not be used in prosecutions from lawyers for architect Studio E, the cladding contractor Harley Facades, current and former employees of the main contractor, Rydon, and officials at the Kensington and Chelsea Tenant Management Organisation.

They threatened that their clients would not otherwise give evidence, in a move attacked as “sabotage” by lawyers for the bereaved and survivors. The inquiry hearings had only restarted eight days earlier after a break of more than a year.

Michael Mansfield QC, representing one group of bereaved survivors and residents, said the demand had “caused immense anxiety, distress and anger”. He opposed the granting of the undertaking on behalf of his clients. Another group of bereaved and survivors stayed neutral on the matter.

The first phase of the inquiry investigating the night of the fire concluded last year that the aluminium composite cladding panels, made by the US industrial giant Arconic and applied to the building, were the main cause of fire spread.

The attorney general’s decision means the inquiry will now restart at 10am on Monday after a delay of almost a month to consider the demand for the undertaking.

“Truth at the inquiry must not come at the expense of justice and prosecutions,” said Grenfell United. “For our continued participation the government must make sure the inquiry process does not undermine prosecutions. If prosecutions are affected by this decision we will hold the government accountable.

“Grenfell was a tragedy but it was not an accident. The people responsible for knowingly encasing our families in a death trap and the people that allowed them to do it must face the full force of the law. We expect criminal prosecutions at the end of this and will not settle for anything less.”

Facebook Twitter Pinterest Suella Braverman, the attorney general, says evidence given by individuals at the inquiry can not be used in any prosecutions against them in the future. Photograph: Chris J Ratcliffe/Getty Images

“Any individual who gives evidence … cannot have that evidence used in any prosecution against them in the future,” the attorney general’s office said in a statement. “The undertaking does not provide immunity from prosecution against anyone.”

The undertaking will only apply to some of the issues being examined in the second phase of the inquiry. It will apply to the inquiry’s examination of the refurbishment and cladding in combustible panels and insulation, the testing, certification and marketing of the cladding products and how the Royal Borough of Kensington and Chelsea and the Kensington and Chelsea Tenants Management Organisation handled complaints from residents and communicated with them.

Many of the survivors and bereaved voiced fears that a broader undertaking could hinder attempts to bring charges as serious as gross negligence manslaughter, which can attract life sentences. The Metropolitan police, who were consulted, were neutral on the application. Detectives investigating the disaster have already seized thousands of documents and have interviewed employees and officials under caution.

The director of public prosecutions and the Health and Safety Executive, which prosecutes some of the potential crimes under investigation, were also consulted, the attorney general’s office said.

“In making this decision I have had the victims of the fire and their loved ones at the forefront of my mind,” Braverman said. “I cannot begin to imagine what they have gone through and I know that the issue of an undertaking will have caused them further anguish.

“The undertaking I am providing to the inquiry means it can continue to take evidence from witnesses who otherwise would likely refuse to answer questions. These questions are important to finding out the truth about the circumstances of the fire. The undertaking will not jeopardise the police investigation or prospects of a future criminal prosecution.”