The Duke of Edinburgh has joked about the number of Filipinos working in the NHS – telling a nurse her home country must now be "half-empty".

Philip, known for his off-the-cuff remarks, made the hospital worker from the Philippines laugh with his comment during a visit to Luton and Dunstable University Hospital.

The Duke reportedly told the unnamed woman: "The Philippines must be half-empty – you're all here running the NHS."

A spokeswoman for the hospital 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.