A former head of the Foreign Office is seeking legal advice following the dismissal of security vetting concerns regarding Peter Mandelson's appointment as UK ambassador to the United States.

The development comes amid questions over the government's handling of Mandelson's diplomatic nomination. Security experts had reportedly raised concerns about the peer's suitability for the high-profile Washington posting, but these assessments were subsequently overruled.

Government ministers have defended Prime Minister Keir Starmer's decision-making process regarding the appointment. They have indicated that Starmer would have reconsidered the nomination had he been properly informed of any significant vetting issues.

The controversy has intensified political pressure on the Prime Minister, with opposition critics questioning the transparency and thoroughness of the vetting procedures for such sensitive diplomatic roles.

Mandelson, a former European Commissioner and veteran Labour politician, was nominated for the ambassador position despite the reported security concerns. The appointment represents one of the UK's most important diplomatic postings given the significance of US-UK relations.

The situation highlights broader questions about the government's appointment processes for senior diplomatic positions and the weight given to security assessments in such decisions.