The Intelligence and Security Committee (ISC) released a damning report on Thursday,accusing Prime Minister Keir Starmer’s government of concealing vital documents related to Peter Mandelson’s appointment as U.S. ambassador and of endangering national security by using unofficial channels such as WhatsApp for official business. The committee said the failures breach professional standards and leave the UK vulnerable.

ISC says government withheld Mandelson vetting files

The ISC alleges that senior officials deliberately redacted and withheld crucial vetting papers that detailed Peter Mandelson’s suitability for the U.S. ambassadorship. according to the committee’s findings, the missing files include security clearances and conflict‑of‑interest assessments that should have been reviewed before the appointment was confirmed.

“The withholding of these documents undermines parliamentary oversight and raises serious questions about the integrity of the appointment process,” the ISC statement read.

WhatsApp flagged as a national‑security risk

The report highlights the government’s reliance on WhatsApp for sharing classified or sensitive information, noting that the platform lacks the audit trails required for official communications. The ISC warned that such practices could expose strategic disccussions to cyber‑espionage and accidental leaks.

“Over‑reliance on unofficial messaging apps is alarming and puts the United Kingdom’s security at risk,” the committee warned , citing multiple instances where policy drafts were circulated via personal devices.

Starmer’s office has not publicly responded

As of the report’s release, the Prime Minister’s office has offered no comment on the specific accusations, only issuing a generic statement that the government “takes the committee’s concerns seriously and will review the findings.” The lack of a detailed rebuttal leaves observers wondering whether the administration will commission an internal audit.

Who approved Mandelson’s US post?

The ISC’s investigation points to a small group of senior officials who signed off on Mandelson’s nomination despite the redacted paperwork. The committee could not identify all members by name, noting that the relevant minutes were among the files that remain classified .

“Without full transparency, it is impossible to assess whether proper due‑diligence was exercised,” the report concluded.

Unanswered questions about the audit trail

The committee could not verify whether any formal audit logs existed for the WhatsApp exchanges, and it remains unclear if any external cybersecurity review has been conducted since the allegations surfaced.

Furthermore, the ISC did not receive a copy of the final security clearance decision for Mandelson, leaving a gap in the official record.