Prince Harry has extended his solo trip abroad without Meghan Markle, Express.co.uk has learned.

According to a well-placed source, the Duke of Sussex, 40, was due to head back to California this weekend to reunite with his wife Meghan, 43, and their two children, but has chosen to prolong his solo trip by an extra few days.

The source adds that the Duke will likely head to Johannesburg and Cape Town for "private time" with family and friends. Another secret visit, which has bizarrely been kept out of his official diary, is also planned.

"It's all very cloak and dagger but Harry has extended his trip abroad by another few days," said the source. "He'll likely go to Johannesburg and then to visit family and friends.

"The Spencers have a home there [in Cape Town] and he has a lot of friends from that part of the world.

"There's also another trip planned which has been blanked out of his diary and he's keen to keep it very private."

Friends of the Sussexes sparked concerns for their relationship earlier this week over the amount of time the couple were spending apart.

Prince Harry has been undertaking several weeks of solo engagements in the United States, United Kingdom and Africa.

The Duke reunited with his old friend Prince Seeiso of Lesotho this week as he gave a passionate speech around a bonfire about the work his Sentebale charity has been doing.

Prior to his trip to South Africa, the Duke embarked on a solo trip to London to attend this year's WellChild awards.

During his brief visit to the UK, Harry did not see either his father, King Charles nor his brother, Prince William.

The Duke's UK visit was preceded by another solo trip to New York City in the United States two weeks ago.

Prince Harry was in the Big Apple to attend a number of events during UN General Assembly High-Level Week and Climate Week.

He spoke at a panel event for The Diana Award, a nonprofit organisation founded after the late Princess Diana's death at age 36 in 1997.

During another appearance, at the Clinton Global Initiative, Harry gave a passionate speech on online harm and called for action to tackle the "pervasive threat" the online world poses for children.

While Harry undertakes his independent travels, Meghan is said to have remained at home in Montecito, California, with their two children, Prince Archie, 5, and Princess Lilibet, 3.

Harry's series of solo visits has led friends to fear that the couple - who have been married for six years - have drifted apart.

"Harry hasn't been home for several weeks now," said the source. "He's conducted a tour on his own which has given him pause for thought and time to reflect on what's important."

The news comes after it was confirmed that another member of Harry and Meghan's staff are to step down from their role at Archewell - bringing the total number of staff to have walked away from the couple in recent years to 19.

Ashley Hansen - who acted as Archewell's communications chief for two years - has announced that she will be leaving to set up her own PR firm.

However, marking a change from the previous 18 staff members to quit and completely walk away, Hansen will continue to act as "advisor" to the couple and will manage the PR for Markle's American Riviera Orchard lifestyle brand.

The Sussexes have been approached for comment.