- Camilla said while on a visit to a vaccination centre in London that Prince Philip is "slightly improving".
- The Duke of Edinburgh was moved to a special unit this week for heart tests; he is being onbserved for a pre-exisiting heart condition.
- "We keep our fingers crossed," she added of her father-in-law.
Queen Elizabeth husband Prince Philip was making slight progress after being admitted to hospital more than two weeks ago, his daughter-in-law said on Wednesday.
Camilla, Duchess of Cornwall, said the 99-year-old Duke of Edinburgh, who was moved to a specialist unit for heart tests on Monday, is "slightly improving".
But she said on a visit to a vaccination centre in London that he "hurts at moments".
"We keep our fingers crossed," she added, with Philip's stay in hospital now his longest ever, raising fears for his health because of his advanced age.
The prince was first admitted to the private King Edward VII Hospital in central London on February 16.
Buckingham Palace said initially that he was expected to stay there for a "few days" after walking in unaided.
Later the palace said that he was being treated for an infection, without specifying further.
But on Monday he was taken to the state-run St Bartholomew's Hospital near St Paul's Cathedral for testing and observation of a "pre-existing heart condition".
In 2011, he had a stent fitted after suffering a blocked coronary artery.
Barts, one of the oldest and most famous hospitals in the country, has a renowned cardiac unit.
The palace said he was expected to stay in hospital at least until the end of this week.
Philip turns 100 on 10 June and his already lengthy stay in hospital has raised concerns because of his age.
Camilla's husband, and Philip's eldest son, heir-to-throne Prince Charles, visited him in hospital last month.
His youngest son Prince Edward and grandson Prince William have both commented on his state of health.
Edward said his father - a former naval officer known for his no-nonsense straight-talking - was looking forward to being discharged.
William said he was in good hands and being closely monitored.
Queen Elizabeth II, who is 94, has herself continued her royal duties despite her husband's illness.
The couple have been in virtual self-isolation at their Windsor Castle home west of London since the start of the coronavirus pandemic last year because of their age.
They have made only brief public appearances, and in January were given a first dose of coronavirus vaccine. The palace has said the duke's illness is not Covid-related.
The monarch spoke to the Chancellor of the Exchequer Rishi Sunak on Tuesday evening ahead of his budget speech on Wednesday, according to tradition.
Philip's illness comes amid fresh controversy involving his grandson Prince Harry, who with his wife Meghan left the royal frontline last year.
The couple have given an interview to the US chat show host Oprah Winfrey, which is due to be aired on Sunday in the US and Monday in SA and expected to add to existing tensions.