Prince William returned Thursday to official duties, visiting a charity ahead of a planned youth centre event, in his first public engagements since his wife Catherine revealed a shock cancer diagnosis.

Heir to the throne as King Charles III's eldest son, William has been largely out of sight since Catherine, Princess of Wales, announced last month that she was undergoing preventative chemotherapy.

The revelation that the 42-year-old was receiving treatment for a cancer discovered following abdominal surgery triggered a wave of support from global leaders, family members, media and the public.

Charles had only weeks earlier revealed he was being treated for an unspecified cancer, leaving the British monarchy in crisis with two of its most senior members simultaneously fighting serious illness.

Carrying out royal duties for the first time since late February, William went to a surplus food redistribution charity in Surrey, southwest of London.

The 41-year-old was then set to tour a youth centre in the west of the capital.

At the Surplus to Supper charity, the prince was to meet volunteers and join chefs in the kitchen to help prepare meals, Kensington Palace said in advance.

Although his first official engagement in weeks, William has been seen in public, most recently at an Aston Villa football match last week with 10-year-old son Prince George.

- 'Time, space and privacy' -

The future king has attended events in an official capacity sporadically so far this year, amid the royal health woes.

In mid-January, Kensington Palace said he was postponing upcoming public engagements to be at his wife's side at the London clinic where she underwent surgery and to help care for their three children.

William then returned to some frontline duties after Kate, as she is widely known, left hospital that month.

But he heightened speculation around her health in February by abruptly pulling out of attending a memorial service, citing a "personal matter".

Within weeks, the princess had revealed her cancer diagnosis in a video message, and William again largely disappeared from public view.

Kate asked for "time, space and privacy" as she completes her treatment.

The couple were notable absentees when senior royals, including Charles, gathered for an Easter church service in Windsor, a long-standing annual tradition for the family.

It was the king's most high-profile public appearance since Buckingham Palace announced his cancer diagnosis in February.

He had been admitted for surgery for a benign prostate condition the month before but was subsequently diagnosed with an unrelated cancer.

The 75-year-old monarch has been continuing behind-the-scenes work and holding some in-person meetings and increasingly attending official events.