ordan's King Abdullah appeared in public Sunday alongside his half-brother Prince Hamzah, state TV showed, their first joint appearance since a palace crisis involving the prince rocked the kingdom.

The images showed a group of Hashemite royals at a mausoleum where their ancestors are buried, on the 100th anniversary since the founding of the kingdom.

The palace Twitter account published a picture of the group at a cemetery with the caption "HM King Abdullah II, HRH Crown Prince Al Hussein... (and) Hamzah bin Al Hussein... visit tomb of HM the late King Abdullah I".

All were dressed in civilian clothes, apart from Hussein, the heir to the throne, who wore military dress.

Jordan is marking 100 years of survival Sunday as a resource-poor country in a war-ravaged neighbourhood, but the palace crisis and the coronavirus pandemic have overshadowed celebrations.

The government had accused Hamzah -- a former crown prince who was sidelined as heir to the throne in favour of Abdullah's son Hussein in 2004 -- of involvement in a conspiracy to "destabilise the kingdom's security".

At least 16 people were arrested.

But Abdullah said Wednesday that Hamzah, who has signed a letter pledging his loyalty to the king following mediation by an uncle, was safe in his palace under his "care".

In an address read out in his name on state television, the king added that "sedition has been nipped in the bud".

'Steps of the ancestors'

Hamzah had been appointed crown prince and heir to the throne in 1999 in line with his father's wishes, but Abdullah stripped him of the title in 2004 and named his own eldest son Hussein in Hamzah's place.

Hamzah in a video message published by the BBC on April 3 claimed he had been placed under house arrest and accused Jordan's rulers of corruption and ineptitude.

Foreign Minister Ayman Safadi then charged that a group of plotters had linked up with foreign parties to destabilise Jordan, but declined to identify them.

After mediation talks, however, Hamzah voiced his loyalty to the king.

"Prince Hamzah pledged before the family to follow in the steps of the ancestors, remain loyal to their mission, and to put Jordan's interest, constitution and laws above all considerations," the king said Wednesday.

A probe into the events continues, the king added.

The crisis laid bare divisions in a pro-Western country usually seen as a bulwark of stability in the Middle East.

Jordan borders Israel and the occupied West Bank, Syria, Iraq and Saudi Arabia. It hosts US troops and is home to millions of exiled Palestinians and many Syrian refugees.

The king's address followed orders issued by Amman prosecutor Hassan al-Abdallat that banned the publication of any information about the alleged plot in order to keep the security services' investigation secret.

The UN human rights office said Friday it was concerned about a lack of transparency surrounding the alleged plot.