Queen Camilla distributed gifts as she deputised for King Charles at the annual Royal Maundy service on Thursday.
The ceremony, a major fixture on the UK royal family's calendar, normally sees the monarch present Maundy money – newly minted coins – to people recognised for their community service.
The queen was welcomed by the Bishop of Worcester, John Inge, as she arrived for the service at Worcester Cathedral.
The king has postponed all public-facing duties while he undergoes treatment for cancer, but is continuing with his behind-the-scenes work.
In a pre-recorded audio address broadcast to the congregation at Worcester Cathedral, he spoke about people who “extend the hand of friendship, especially in a time of need”.
“In this country, we are blessed by all the different services that exist for our welfare,” the king said, in the message which was recorded along with a bible reading earlier this month.
“But over and above these organisations and their selfless staff, we need and benefit greatly from those who extend the hand of friendship to us, especially in a time of need.”
He added: “It is for me a great sadness that I cannot be with you all today.
“This act of worship here in Worcester Cathedral reminds me of the pledge I made at the beginning of the 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.”
The king did not directly refer to Catherine, the Princess of Wales, who revealed last Friday in a video that she is also receiving treatment for cancer.
But some royal watchers have interpreted his words as a reference to the support that he and the princess have received over their health issues.
The religious service marks the start of the Easter weekend and originated in the commandment Christ gave after washing the feet of his disciples the day before Good Friday.
Today sovereigns no longer wash the feet of the needy, as they did in medieval times.
Instead, 75 women and 75 men, signifying the king's age, were presented with two purses, one red and one white, filled with Maundy money. The tradition began in 1662, when Charles II gave out coins.
Both the king and queen are due to attend an Easter service at the chapel at Windsor Castle on Sunday, which will be the monarch’s first major appearance since his February diagnosis.
They will be accompanied by members of the royal family at St George's Chapel.
The event is expected to be smaller than usual, with a reduced number of royals present in order to avoid the health risks associated with large crowds.
Prince William and the Princess of Wales are not expected to attend.
Officials have not disclosed what form of cancer the royals are suffering from, but they have confirmed the king's is not related to his recent treatment for a benign prostate condition.
Queen Camilla through the years - in pictures
