The pre-recorded audio was broadcast in his absence at a Royal Maundy service at Worcester Cathedral on Thursday ahead of the Easter weekend.

The King, who announced in February he was undergoing cancer treatment, talked of his "special prayer" this Easter and expressed his "great sadness" of being unable to attend.

"The Maundy service has a very special place in my heart," he said, after a Bible reading recounting Jesus washing his disciples' feet.

He said the verse, from the Gospel according to St John, "has its origin in the life of our Lord, who knelt before his disciples, and to their great surprise, washed their trouble-weary feet".

The monarch said in doing so, Jesus set "an example of how we should serve and care for each other" - and how as a nation "we need and benefit greatly from those who extend the hand of friendship to us, especially in a time of need".

The 75-year-old, who acceded to the throne 18 months ago, said it reminded him of the pledge he made at the start of his Coronation service to follow Christ's example - "not to be served, but to serve".

"That I have always tried to do and continue to do with my whole heart," he said.

"It is my special prayer today that our Lord's example of serving one another might continue to inspire us and to strengthen all our communities."

He added: "May God bless you all this Easter."

The major event in the royal calendar sees Maundy money - newly minted coins - distributed to community stalwarts by the head of state in recognition of their service, with the Queen deputising for the King in the ceremony, a first for a Queen Consort.

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The King, however, continued his low-key duties and held private audiences with ambassadors at Buckingham Palace.

The monarch - who has stepped back from large-scale public duties while receiving outpatient treatment - was pictured sitting at his desk in Buckingham Palace's 18th Century Room as he recorded his Easter message in mid-March.

While the King did not directly refer to his and his daughter-in-law's health, his words will be interpreted as reflecting on the nation's response to his and Kate's challenges.

He told last month how he had been reduced to tears by the messages and cards of support he received from well-wishers.

On Wednesday, the Queen, during a visit to Shropshire, was given posters from well-wishers for the Princess of Wales, and said Kate would be "thrilled" to receive them.

The King's message comes as he prepares to attend church on Easter Sunday with the Queen - his most significant public appearance and major royal engagement since his cancer diagnosis.

But there will be a reduced number of royals present to avoid the health risks associated with large crowds.

Prince William, the Princess of Wales, and their children Prince George, Princess Charlotte and Prince Louis will not be present.

The family are spending the Easter holidays together following Kate's announcement she is being treated for cancer.

Kate revealed she is undergoing preventative chemotherapy in a video message to the nation on Friday.

The statement followed weeks of global social media speculation and conspiracy theories about her whereabouts after she had not been seen on official engagements since last December.

The 42-year-old had planned abdominal surgery in January which she said was successful.

It was initially thought her condition was non-cancerous, but tests after the operation found cancer had been present.