The Duke of Sussex is expected to return to the UK from the USA for the funeral of his grandfather, the Duke of Edinburgh, despite widespread travel restrictions.
However, it is thought unlikely that the Duchess, heavily pregnant with their second child, will join him.
Prince Harry, 36, was extremely close to Prince Philip, although he is not thought to have seen him in person since the autumn of 2019.
A royal source told the New York Post: "He will, of course, be there, no matter how difficult relations are between the Sussexes and the family."
Current rules state that the majority of people attempting to travel to the UK must test negative for Covid within 72 hours of their flight and then quarantine for 10 days on arrival.
There is an exemption for people attending the funeral of a close family member, although Prince Harry would have to self-isolate at all other times.
He spoke of his grandfather during a recent television interview with James Corden, fondly describing how he conducted Zoom calls.
"We've Zoomed them a few times. They've seen Archie running around," he said, laughing as he recalled how the Duke had slammed his laptop shut to end a call.
The Duke and Duchess of Sussex's website has been transformed into a memorial page to the Duke of Edinburgh.
A short message on archewell.com, set against a dark background, says: "In loving memory of His Royal Highness The Duke of Edinburgh. 1921-2021. Thank you for your service... you will be greatly missed."
A spokesman for the Sussexes declined to comment.
Watch: The wonderful life of Prince Philip, The Duke of Edinburgh