The army did not seek approval from Kensington Palace before announcing she would be present at the event on 8 June in text on its website. Her name has now been removed from the event's description.

The 42-year-old future queen has not been seen on official duties since late December, when she was pictured on a Christmas Day walk with other members of the Royal Family in Sandringham, Norfolk.

She was admitted to the London Clinic - the private hospital where the King underwent treatment for an enlarged prostate - for a planned abdominal operation on 16 January.

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The palace has previously said the princess would not return to public duties until after Easter.

The announcement of her scheduled appearance at Trooping the Colour came as a surprise and it was not clear if it was due to be her first official appearance following her surgery.

Kensington Palace had not confirmed her attendance.

There are three Trooping the Colour sessions this summer - with the event's website originally saying the first was to be reviewed by Major General James Bowder on 1 June, the second to be reviewed by the Princess of Wales on 8 June and the third reviewed by the King on 15 June.

Now the website says Trooping the Colour will take place on 15 June only with no mention of who is reviewing the parade.

Some 1,400 soldiers of the Household Division and The King's Troop Royal Horse Artillery will parade on Horse Guards Parade.

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In addition to Kate, there is uncertainty about the health of King Charles, 75, who is being treated for cancer and was also scheduled to attend the event on 15 June, according to the earlier version of the MoD's site.

It is understood that palace officials continue to plan for major royal events while remaining flexible with a view to the royals' health.

There has been speculation about the princess's health on social media.

The palace, however, has only said her surgery was not cancer-related and she wishes her personal medical information to remain private.