Thirty-six years after Richard Nixon testified to the Watergate grand jury, a federal judge yesterday ordered the first public release of the transcript about the break-in that drove him from the presidency.

The 297-page transcript will not be available immediately but will be held until the government decides whether to appeal. In the American legal system, a grand jury is seated to determine whether a law has been violated and whether sufficient evidence exists to warrant prosecution.

The Obama administration opposed the transcript's release, chiefly to protect the privacy of people discussed during the former president's testimony who are still alive.

Nevertheless, US District Judge Royce Lamberth agreed with historians who sued for release that the historical significance outweighs arguments for secrecy, because the investigations are long over and Nixon has been dead 17 years.

Nixon was interviewed privately near his California home for 11 hours over two days in June 1975, 10 months after he became the first US president to resign the office. Two grand jurors were flown in and the transcript was read to the rest of the panel sitting back in Washington. It was the first time a former US president had testified before a grand jury. Later, Bill Clinton became the first sitting president to do so during the Monica Lewinsky investigation.

At the time of his testimony, Nixon could not be prosecuted for conduct related to Watergate because he had been pardoned by President Gerald Ford. Ten days after Nixon's testimony, the third Watergate grand jury was dismissed without handing up indictments.

The historians say the testimony could help resolve continuing debate over Nixon's knowledge of the break-in at Democratic Party headquarters at the Watergate complex in Washington and his role in the cover-up that protected the conspirators for a time.

"Nixon knew when you testified before a grand jury you exposed yourself to perjury, so I'm betting he told the truth," said University of Wisconsin Professor Stanley Kutler, who filed the lawsuit along with four historians' organizations. Kutler, author of "Abuse of Power: The New Nixon Tapes," previously successfully sued to force the release of audio recordings Nixon secretly made in the Oval Office. "Now, what did he tell the truth about? I don't know."

Newspapers reported at the time of Nixon testimony that he was questioned about an 18 1/2-minute gap in tape recordings from the president's Oval Office, changes made to White House transcripts of the recordings, his administration's use of the Internal Revenue Service, the government's tax collectors, to harass his political enemies and a $100,000 (£60,000) campaign contribution from billionaire Howard Hughes. The details of what the president said have never leaked out.

Several Watergate figures filed declarations in support of the petition, including Nixon's White House counsel John Dean, who served prison time for his role in the scandal. Dean wrote that Nixon's testimony covers topics that the president only vaguely discussed in his memoirs and his revelations to the grand jury would help stop "those wanting to twist and distort history."

In rejecting the Obama administration's arguments for privacy, Lamberth pointed out that most of the surviving Watergate figures have either written about it, given interviews that already are public or spoken under oath in testimony about their involvement. "The court is confident that disclosure will greatly benefit the public and its understanding of Watergate without compromising the tradition and objectives of grand jury secrecy," Lamberth wrote.

Justice Department spokesman Charles Miller said yesterday that government attorneys were reviewing the ruling.

Other courts have on occasion ordered the release of grand jury records because of their historical impact, including those investigating espionage allegations against Alger Hiss and Julius and Ethel Rosenberg.