AMMAN • Jordan's Deputy Prime Minister Ayman Safadi yesterday said King Abdullah II's half-brother and former crown prince, Hamza bin Hussein, had been liaising with foreign parties over a plot to destabilise the country and had been under monitoring for some time.

The authorities had intercepted communications between Prince Hamza and foreign parties over the timing of steps to undermine Jordan's security, Mr Safadi said at a news conference in the capital, Amman.

The security services have asked for those involved in the plot to be referred to the state security court, he said.

More than 16 people have been taken into custody.

"There was an effort to target Jordan's security and stability, this effort was foiled," he said. He gave no evidence to back up his claims.

The army had earlier asked Prince Hamza to cease "movements and activities that might be used to target Jordan's security and stability", said the state-run Petra news agency.

Hasan bin Zeid, a member of the royal family, was also held on security grounds, along with several others, including former minister Bassem Awadallah, Petra said.

The crackdown comes as Jordan, a US ally that is home to as many as two million Palestinians and normalised relations with neighbouring Israel in 1994, struggles with a worsening squeeze on its finances and a resurgence of Covid-19 cases that prompted the government to renew restrictions on movement.

The US had provided the Middle East kingdom with US$700 million (S$941 million) in August.

"We are closely following the reports and in touch with Jordanian officials," US State Department spokesman Ned Price said in a statement. "King Abdullah is a key partner of the United States, and he has our full support."

Security personnel and armoured vehicles were seen parked outside royal palaces and patrolling the Dabouq neighbourhood of Amman last Saturday.

The Washington Post said earlier that Prince Hamza, the eldest son of the late King Hussein and his fourth wife Queen Noor, was under house arrest at his palace in Amman. It cited a senior Middle East intelligence official briefed on the events as saying that there was an ongoing investigation into an alleged plot to unseat King Abdullah.

Prince Hamza, in a six-minute video provided to the BBC by his lawyer, said he was "not part of any conspiracy".

"I had a visit from chief of general staff of the Jordanian armed forces this morning in which he informed me that I was not allowed to go out, to communicate with people or to meet with them because in the meetings that I had been present in - or on social media relating to visits that I had made - there had been criticism of the government or the king," the prince said in the video. He added that his Internet connection and phone lines had been cut.

Prince Hamza was the crown prince for four years before the title was transferred in 2004 to the current king's eldest son, Prince Hussein. Prince Hamza has occupied various roles, including brigadier, in the Jordanian army.

Saudi Arabia, the United Arab Emirates, Qatar, Egypt and other Arab states have expressed support for King Abdullah.

The Saudi royal court said in a statement that "the kingdom affirms its full support, with all its capabilities, to all decisions and measures taken by King Abdullah and His Highness Prince Al Hussein bin Abdullah II, the Crown Prince, to maintain security and stability".

The United Arab Emirates' Ministry of Presidential Affairs stressed the country's full support for decisions and measures taken by King Abdullah and his crown prince to maintain Jordan's security and stability and "to defuse any attempt to impact them".

"The Biden administration would view the potential of a failed state as detrimental to regional stability," said Mr Ayham Kamel, the New York-based head of Eurasia Group's Middle East and Africa research team.

"The Israeli security establishment would not look favourably towards any real instability in Jordan that triggers a Palestinian crisis."

REUTERS, BLOOMBERG