The Cabinet Office has blamed an “administrative error” for mistakenly sharing official papers referring to Andrew Mountbatten-Windsor.

A No 10 file from 2004 and 2005 relating to royal visits – released as part of the government’s annual transfer of records to the National Archives under the 20-year rule – was briefly made available to journalists before being withdrawn.

The version originally released under embargo included minutes of a meeting about the overseas travel of various royals, including the then-Duke of York, who was serving as a UK trade envoy.

That information was later redacted from the file before it was made public on Tuesday at the National Archives in Kew, west London.

The Cabinet Office, which is responsible for transferring the files to the National Archives, said the documents were never intended for public disclosure.

A spokesman said: “All records are managed in line with the requirements of the Public Records Act. Any release is subject to an extensive review process, including engaging expert stakeholders.”

Anti-monarchy campaigners said there was no justification for withholding the papers, particularly given Andrew has since been stripped of royal titles over his links to deceased sex offender Jeffrey Epstein. Andrew has always denied any claims of wrongdoing.

Graham Smith, chief executive of campaign group Republic, said: “The royals are one of the most secretive institutions in the UK. These documents should be released without fear or favour, to allow the public to make informed judgements about the royals.”

The minutes themselves, seen by journalists before being pulled, appeared largely routine.

They discussed Andrew’s travel plans as a trade envoy – a role that earned him the nickname “Airmiles Andy” – including visits to China, Russia, southeast Asia and Spain.

Other papers released to the National Archives reveal the Foreign Office ruled out military action to overthrow Zimbabwe’s long-time leader Robert Mugabe, despite mounting frustration in Tony Blair’s government over his refusal to relinquish power.

An options paper drawn up in 2004 warned that any UK-led intervention would be politically isolated, costly and lack a viable exit strategy, concluding it was not a “serious option”.

The Foreign Office had to admit there were few good options for ratcheting up the pressure on Mugabe who, at the age of 80, remained “depressingly healthy” and determined to stay on until he had secured a succession to his liking.

The papers also reveal Downing Street was forced to apologise after then-Prime Minister John Major’s birthday telegram to the Queen Mother in 1994 was addressed in an “improper manner”.

The Queen Mother’s private secretary contacted No 10 to complain, although the files do not explain what caused the offence. Officials said the message had left Downing Street correctly but blamed an error in transmission and suggested telegrams should be abandoned altogether.

There is also evidence of the limits placed on transparency under the Freedom of Information Act. Newly declassified papers show officials refused to release details of a conversation between Blair and French president Jacques Chirac following the death of Diana, Princess of Wales in Paris in 1997.

While papers relating to Diana’s death and funeral arrangements were released, a memo summarising the Blair-Chirac discussion was ruled out of scope.

Officials argued it was “fundamentally not in the public interest” to disclose private conversations between world leaders, warning doing so would inhibit frank exchanges in future.

Also revealed in the files were the ambitious and ultimately abandoned plans for a wholesale redevelopment of Downing Street under Blair.

Briefing papers dated March 2005, just two months before the general election, describe a multi-million-pound project, codenamed Project George, to overhaul the ageing estate, parts of which date back to the 17th century and had not undergone a major refurbishment since the 1960s.

The proposals included a two-storey “subterranean suite” beneath the No 10 garden, featuring a 200-seat conference room that could double as a “safe haven” in the event of a terror attack.

There were also plans for an underground service road to separate VIP visitors from refuse collections, a new staff entrance, a cafe and “recreation facilities” in the basement.

Officials warned that failing sewers, power supplies and IT systems were causing an “unacceptable failure of critical services”.

The plans, to be funded through the private finance initiative over 30 years, extended to Nos 11 and 12 Downing Street and 70 Whitehall – the home of the Cabinet Office – which would have been given a new glass-fronted extension and blast-resistant glazing. The files do not explain why the plans were dropped.