Prince William returns to work after Kate's surgery, King Charles's cancer diagnosis

London: Prince William on Wednesday returned to royal duties for the first time since his father, King Charles III, was diagnosed with cancer and his wife, Kate, was hospitalised for abdominal surgery.

The Prince of Wales carried out an investiture ceremony at Windsor Castle on Wednesday and is expected to later attend a gala fundraising dinner for London’s Air Ambulance Charity in the evening.

He is expected to take on extra engagements in the King's absence.

On Wednesday, No 10 said the prime minister's weekly audience with the King would take place over the phone, BBC reported.

Downing Street does not usually comment on the meetings but said it agreed with the Palace "in this specific instance to confirm that they will be speaking on the phone later", the report added.

The King has travelled to Sandringham in Norfolk with the Queen. His "regular treatments" for an unspecified cancer began on Monday.

Prince William's return to public duties follows a three-week absence which began after Catherine, the Princess of Wales, underwent surgery.

While Buckingham Palace has stressed the King will continue to perform his formal constitutional functions, Prince William will stand in for him at some events.

The Princess of Wales is continuing her recovery at home after spending a fortnight in hospital.

The father-of-three had taken a break from official engagements to care for Princess Kate and their children after she spent 13 days recovering in hospital from her procedure.

But as King Charles is forced to postpone public engagements as he undergoes cancer treatment, other members of the royal family, including William, have stepped up.

His busy day comes as his brother Prince Harry reportedly stayed in a London hotel on Tuesday night following his brief reunion with their father.

Prince Harry flew from California to see the King for a meeting that lasted roughly 30 minutes.