A “Hillsborough law” will be introduced in Parliament before the next anniversary of the 1989 football stadium tragedy, Sir Keir Starmer has confirmed.

The Prime Minister announced that legislation would force public bodies to co-operate with investigations into major disasters or potentially face criminal sanctions will be in progress before April 2025.

A terrace crush at an FA Cup semi-final in Sheffield on 15 April 1989 resulted in the deaths of 97 Liverpool fans.

The prime minister said a “law for Liverpool, a law for the 97 that people shouldn’t have had to fight so hard to get will be delivered” before the 36th anniversary.

The Hillsborough Law will introduce a legal duty of candour on public bodies.

Officials or organisations that mislead or obstruct investigations could potentially face criminal sanctions.

Sir Keir will say he is honouring a commitment he made during a speech in Liverpool two years ago.

He said: “That was when I promised, on this stage, that if I ever had the privilege to serve our country as prime minister, one of my first acts would be to bring in a Hillsborough Law – a duty of candour.

He said it will also be supported by a code of ethics for public bodies and authorities to address the wider culture of defensiveness seen in the wake of public disasters such as the Post Office Horizon IT system, infected blood scandal, Windrush.

Margaret Aspinall, who lost her son James at Hillsborough when he aged 18, said the fact Sir Keir had phoned her last night to explain what the new legislation would look like, was “respect for all the hard work” the families and survivors.

“This is about the ordinary people who’ve stayed together,” she said.

“Who stayed together and fought for so long to achieve this. Its took a long time but we’ve achieved it.

“It is a lovely legacy of the 97. Their deaths will have changed things so much for the good of the ordinary people.”

Charlotte Hennessy, whose father Jimmy died in the disaster, has since campaiged for the truth about what happened.

She said it was only after the Hillsborough Independent Panel report she “realised the extent of how much information was withheld from us as a family”.

“Hopefully going forward this will stop other people from having such a long fight to find out what happened to their loved ones,” she said.

Mayor of Greater Manchester Andy Burnham, who was instrumental in getting the Gordon Brown Labour government to set up the Hillsborough independent panel, said ahead of the announcement: “It says something about the measure of [Keir Starmer] that he is coming straight back to deliver on the commitment to the Hillsborough families and others.”

He said the law was not about solely about “the injustice of Hillsborough, it’s about future cover-ups… and active cover-ups”.

Burnham added that he believed the changes the law would bring could make a huge difference to the veterans affected by being forced to witness nuclear bomb testing in the 1950s whom he said he firmly believed were victims of a Ministry of Defence cover-up.

The draft new law will see the government take forward recommendations made by Bishop James Jones in his 2017 report which examined the experiences of the Hillsborough families in the years following the disaster.

An independent public advocate (IPA) would be sent to the scene of any future public disaster, playing a pivotal role in ensuring victims, survivors, and bereaved families get the information and support they need.

The advocate is expected to be in post by next summer. They would inform victims about sources of support, legal advice and services available to them.

The role would also help victims understand actions taken by public authorities in relation to the incident, including how to navigate inquiries, inquests and other formal processes that may follow a public disaster.

The IPA would also communicate with public authorities on behalf of victims.

Elkan Abrahamson, a solicitor at Broudie Jackson Canter and a director of the Hillsborough Law Now Campaign (HLN), said: “We and all the families are delighted to hear the renewed commitment from the Prime Minister that a Hillsborough Law will be brought in by next April.

“However, there remains a lot of work to do to ensure a Hillsborough Law loses none of the effectiveness of the original bill.

“The HLN campaign has grown significantly and is now a coalition of families bereaved by state failures who will not give up until they see the right act on the statute book.

“The campaign stands ready to assist the government in making this law a reality.”

Deborah Coles, director of INQUEST, a charity which provides support to people bereaved by state-related deaths, said: “There are few occasions we can celebrate success and today is a step forward in providing a legacy for the 97 so that others do not have to go through the pain and trauma of decades of campaigning.

“This is the result of the incredible power of families standing together to demand justice accountability and change.”

She added: “A massive thank you to you all and we hold in our thoughts those who have been killed or harmed by the state.”