LONDON — Chief Secretary to the Prime Minister Darren Jones told the House of Commons on Tuesday that the next tranche of documents relating to Peter Mandelson's appointment as UK ambassador to Washington would be published in June. Jones defended the government's decision to redact and withhold some material, saying ministers were within their rights to do so for national security reasons.

The next set of documents is understood to run to thousands of pages. Jones refused to confirm that they would be released before the Makerfield by-election, which is likely to be held on 18 June.

MPs voted earlier this year to compel the government to publish all documents related to Mandelson's appointment, with redactions permitted for national security and international relations. Under pressure from MPs on all sides, the government accepted that redactions should be agreed by the Intelligence and Security Committee, which oversees the release process.

Addressing the Commons, Jones said ministers had legitimate reasons to keep some information confidential. "I am sure members across the house will recognise there is no public interest in the government publishing the names and contact details of junior officials or their telephone numbers," he said.

Jones also defended withholding material gathered during security vetting. "The raw data that is collected as part of those investigations related to how much money you have in a particular account or who you may have had a personal relationship with in the past recorded data would never be published because if we did so, people would feel unable to answer those questions honestly and frankly in any U.S. security vetting future investigation, which would undermine the very basis of our national security system," he said.

The Intelligence and Security Committee published a statement on Friday accusing the government of redacting and withholding documents against the wishes of parliament and said ministers had not complied with the terms of the vote. Members of the committee said ministers had redacted personal information such as email addresses and phone numbers and had withheld Mandelson's entire vetting file, including his interview responses.

Kevan Jones, a peer and chair of the Intelligence and Security Committee, said the dispute was about transparency over the redaction process. "This is not a cover-up, this is about making sure that when the documents are released to parliament, parliament and the public know what has been redacted and the reasons for doing so," he said.

Shadow minister Neil O'Brien told the Commons the government's handling of the matter conflicted with what MPs had agreed. "To say that the government has applied redactions to the documents sent to the Intelligence and Security Committee beyond the scope agreed by the House, and has also withheld documents entirely from the Committee, is an extremely serious matter that completely undermines what this House agreed," he said.