A major betting company in Britain has stopped taking bets on when Prince Harry and his wife Meghan's baby will be born, believing on Friday that it has already secretly arrived.

Paddy Power said it had suspended bets on when the Duke and Duchess of Sussex's first-born would enter the world following a spike in wagers.

Queen Elizabeth II's eighth great-grandchild will be seventh in line to the throne. When the pregnancy was announced, commentators believed the baby was due in late April.

"We've suspended betting on which day Harry and Meghan's baby will arrive following a huge increase in wagers... which indicate to us that someone knows something," said Paddy Power.

"That, combined with the rumours and speculation, has us convinced that the royal arrival has already happened."

However, other bookmakers have not followed suit.

"We don't think they have had a baby," said William Hill spokesman Rupert Adams.

"A huge number of people would be involved in the birth. I think it would be difficult to keep it that secret."

William Hill were offering bets on whether the baby would be born in April or May, so stopped taking wagers on Wednesday.

At Ladbrokes, punters can still bet on the date of birth, with Friday and Saturday the joint favourites at 2/1, then Sunday at 5/2 and Monday at 3/1.

Harry and Meghan have decided to keep the plans around the arrival of their baby under wraps, and will only share the news once they have had time to celebrate privately.

Harry last appeared in public on Sunday to congratulate the London Marathon winners, a visit that was not announced in advance due to the uncertainty over the birth date.

The prince is due to visit the Netherlands on Wednesday and Thursday to launch the one-year countdown to the 2020 Invictus Games in The Hague, the Paralympics-style event he founded for wounded military veterans.