Hillsborough files to be made public
Information commissioner Christopher Graham ruled that the information was in the public interest.
He said: "Support for disclosure of information relating to the Hillsborough disaster was expressed by the previous government and has been reconfirmed by the current government, and the commissioner also believes that the specific content of the information in question would add to public knowledge and understanding about the reaction of various parties to that event, including the government of the day, in the early aftermath."
Ninety-six Liverpool fans died in the crush at Hillsborough Stadium in Sheffield on 15 April 1989, where the club was playing an FA Cup semi-final against Nottingham Forest.
An inquiry found that the main reason for overcrowding was the failure of police control.
The commissioner's judgment may still be subject to an appeal. If there is no appeal, the Cabinet Office has 35 days to comply with the order.
Mr Graham's judgment relates to a Freedom of Information request more than two years ago, which was refused by the Cabinet Office. This was followed by an internal review which upheld the refusal, prompting the complainant to ask the Information Commissioner's Office to review the request last year.
In his judgment, the commissioner hit out at the Cabinet Office for "unjustified and excessive" delays. He ordered the government to publish information relating to the Hillsborough disaster provided to Mrs Thatcher, then prime minister, and the minutes of meetings she attended on the matter.