The families of those who died in the 1989 Hillsborough disaster are bracing themselves for a "hard hitting" report about the tragedy which cost 96 lives.

The independent report, chaired by the Bishop of Liverpool, the Right Reverend James Jones, has spent the past two years probing more than 400,000 previously unseen documents from South Yorkshire Police, the ambulance service and other bodies.

A 1990 report into the tragedy, led by Lord Justice Taylor, concluded that the main reason for the disaster was a failure by South Yorkshire Police to control the crowd.

Hillsborough campaigners now believe the documents will reveal a cover-up in the wake of the disaster. Sheila Coleman, spokesperson for the Hillsborough Justice Campaign, told IB Times UK:

"I believe that tomorrow the evidence that comes out will be quite hard-hitting and people will see the extent of the cover-up.

"If CCTV camera footage went missing on the day of the disaster from the control room, which was effectively a crime scene, then they've had 23 years to get rid of other evidence.

"So while I'm sure lots of evidence will come out I think it will be naïve to assume that all evidence has been seen by the panel."

While Coleman was confident the documents will offer some sort of closure for the family, she said she doubted "that all papers still exist".

However Coleman does believe that, 23 years after the Hillsborough disaster, the official documents will finally reveal who is responsible for the deaths and the alleged subsequent government cover-up.

Coleman said: "Best-case scenario is that the report highlights that Hillsborough was a disaster that was avoidable and it was the fault of the police - as was highlighted by Lord Justice Taylor as long ago as 1989.

"Following on from that there was a cover-up which was sanctioned by Margaret Thatcher and the Tory government... Thatcher protected South Yorkshire Police as payback and a thank you for how they had policed the miner's strike."

Coleman added that, as a result of tomorrow's revelations, she hopes "the people responsible for the disaster and the subsequent cover-up are subsequently prosecuted, not individuals, but at a corporate level.

"The worst case scenario is that Margaret Thatcher's name is not mentioned, or only mentioned in passing, and her role is minimised."

'The Truth will have its own power'

Andy Burnham is the MP for Leigh in Greater Manchester and a key figure in setting up the independent panel which has probed the papers.

Before the documents are displayed to the victim's families prior to general release, Burnhan warned they will reveal senior authorities have "questions to answer" and said the information disclosed "will be more shocking than many people realise."

Speaking to the Mirror, Burnham said: "There will be many ­individuals with questions to answer on Wednesday into Thursday night, but the truth will have its own power.

"I know enough about Hillsborough to know a national apology from the Prime Minister is justified. I hope Mr Cameron responds in the right way.

"The closer we get, I'm confident the full truth will be told. That is an enormous thing."

One of the controversies in a 1991 inquest by coroner Dr Stefan Popper was the introduction of a cut-off time. The coroner ruled that all victims had died by 3.15 on the day of the tragedy.

Burnham added: "After the disclosure, my thinking will turn to a new inquest as the sheer cruelty of the 3.15pm cut-off point, when the coroner ruled that all Liverpool fans had died by this time, can't be allowed to stand.

"I, like the families, cannot accept a verdict of accidental death."

This view, that a new inquest should be ordered to investigate evidence after 3:15pm, is shared by Coleman

She added: "If that doesn't happen then at a minimum there should be a replacement verdict which incorporates a lack of care. People are saying they would like unlawful killing but I can't see that happening."

Update: Hillsborough the Truth: Disaster Documents Released - LIVE