The Duke of Edinburgh has joked about the number of Filipinos working in the NHS - telling a nurse her country must now be "half-empty", it has been reported.
Philip, who is famed for his off-the-cuff remarks, made the hospital worker from the Philippines laugh with his comment during a visit to open a cardiac centre.
BBC Online reported the Duke as saying to the unnamed woman: "The Philippines must be half-empty - you're all here running the NHS."
Philip's remark came during a visit to Luton and Dunstable University Hospital on Tuesday, where he officially launched the multimillion-pound cardiac centre. A spokeswoman for the hospital described the royal visit as a huge boost for staff morale and said the Duke was in a jovial mood, making jokes throughout his tour.
Philip had a stent fitted to clear a blockage in a coronary artery in December 2011 and when, during the visit, he was given a gold-plated stent, he quipped that he now had a spare.
The Duke is well known for his outspoken comments and famously told British students during a 1986 state visit to China: "If you stay here much longer, you'll all be slitty-eyed."
He also once told a group of deaf youngsters: "Deaf? If you are near there, no wonder you are deaf," referring to a school's steel band.
He also asked Susan Edwards, who is blind, uses a wheelchair and has a guide dog: "Do you know they have eating dogs for the anorexic now?"
The hospital spokesman said of the visit: "Staff greatly enjoyed the opportunity to meet the Duke of Edinburgh, and we regard all personal conversations he had with our staff and guests as private and therefore would not comment on them."
Buckingham Palace said it did not comment on private conversations.