LONDON - Britain's Prince Harry and his American fiancee Meghan Markle have invited 600 guests to their wedding in May although who is on the list is not being revealed yet, his office said on Thursday.

Kensington Palace said all those invited to the May 19 ceremony at St George's Chapel, Windsor Castle, his grandmother Queen Elizabeth's home west of London, would also be invited to the lunchtime reception afterwards.

Later in the evening, 200 guests will attend a private reception at nearby Frogmore House which will be hosted by Harry's father, Charles, the Prince of Wales.

The palace said the invitations, die-stamped in gold with the edges bevelled and gilded, had been sent out this week. However, it said no details of who had been invited would be released at this stage.

"His Royal Highness the Prince of Wales requests the pleasure of the company of ... at the Marriage of His Royal Highness Prince Henry of Wales with Ms Meghan Markle," the invitation reads.

Men are instructed to wear "Uniform, Morning Coat or Lounge suit" and women "Day Dress with hat".

About 1,900 people were invited to the lavish wedding of Harry's elder brother William and wife Kate at London's Westminster Abbey in 2011.

Their guest list included celebrities such as singer Elton John, ex-soccer player David Beckham and his fashion designer wife Victoria along with royalty from around the world and political figures, although not international heads of state.

Some British newspapers have speculated that Harry might invite former US President Barack Obama whom he interviewed for BBC radio at Christmas, but not current President Donald Trump.

Royal biographer Claudia Joseph said Harry would not want to do anything that would have political repercussions that could cause embarrassment for the queen.

"Harry adores his grandmother and is not going to want to upset her," Joseph, author of "How to Dress Like a Princess", told Reuters. "The last thing he's going to want to do is spark World War Three."

She said the choices Harry and Markle had made so far indicated they would have a more personal wedding than William and Kate.

"I think they want to do it their way," she said. "I think it will be much less stuffy, much less pomp and circumstance, and much warmer and more natural."

The palace has already announced that more than 2,500 members of the public and figures from charities the couple support would be invited to watch the arrivals of the bride and groom and their guests, and to see them depart on a carriage procession around Windsor after the ceremony. 

Reuters