In a six-minute video provided to the BBC by his lawyer, he said he was "not part of any conspiracy".
"But at the end, the security and stability of Jordan are above all consideration and all the necessary legal procedures will be taken to protect them", Safadi said. He did not provide specifics on the alleged plot or say what other countries were purportedly involved.
What was the reaction in Jordan?.
Hamzah's mother, American-born Queen Noor, defended her son and the others, tweeting that she was "praying that truth and justice will prevail for all the innocent victims of this wicked slander". "God bless and keep them safe".
Hamzah - a former crown prince stripped of that title by Abdullah in 2004 - and the others had worked with foreign parties to "undermine the security" of Jordan, Deputy Prime Minister Ayman Safadi said. But the prince has disputed this in a video message.
Stability in Jordan and the status of the king have always been a concern throughout the region, particularly during the Trump administration, which gave unprecedented support to Israel and sought to isolate the Palestinians, including by slashing funding for Palestinian refugees.
His comment came during a meeting of top officials as they mark the 100th anniversary of the Jordanian state.
"The secretary-general of the Arab League expressed full solidarity with the measures taken by the Jordanian leadership to maintain the security of the kingdom and maintain the stability", the Arab League said in a statement on its Facebook page, citing Ahmed Aboul Gheit.
Awadallah has been a close confidant of King Abdullah II of Jordan, as he has held a number of leading positions since the 1990s, including being the Economic Secretary to the Prime Minister of Jordan since 1992 and the Director of the Economics Department at the Royal Hashemite Court until 2001. He was also an adviser to Saudi Crown Prince Mohammed bin Salman.
Safadi said Awadallah was in contact with the so-called "foreign opposition", which aimed to incite the people against the Jordanian state.
Prince Faisal also reiterated the Saudi stance that a normalisation of ties with Israel would only be possible after a peace settlement between Israel and the Palestinians.
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While very little information has been revealed about Sharif Hassan Bin Zaid, including his ties with Saudi Arabia, alleging financial investments he has in the neighboring kingdom, the internet was filled with accounts on the former royal aid now under arrest; Bassem Awadallah.
The prince said he was ordered confined at home and to refrain from speaking out. The individual said the recording is a few days old and was made after the army chief threatened the prince.
Hamzah, however, remained a popular figure of Jordan's royal family, bearing an uncanny resemblance to his father, and was seen as modest and religious. "This is why we are now witnessing what has happened".
He lashed out at Jordan's "ruling system", saying several of his friends had been arrested, his security detail removed and his internet and phone lines cut.
The report noted that despite the political estrangement between Amman and Tel Aviv and the personal anger that King Abdullah II has shown towards Netanyahu, two years ago, the Jordanian king has ensured that his army officers conveyed messages of assurances to their Israeli counterparts that "things are under control". However, regional powers and Western allies, including the United States and United Kingdom, have all voiced support for the king.
In a separate statement, Foreign Minister Prince Faisal bin Farhan Al Saud said Jordan's stability and prosperity was the "basis for the stability and prosperity of the whole region" and vowed "firm and lasting" support for it.
What is the situation in Jordan?.
Public anger has also increased since nine COVID-19 patients died when oxygen ran out in a newly built state hospital, exposing negligence blamed on official mismanagement and corruption.
The Washington Post had first reported that the former crown prince was "placed under restriction" as part of a probe into an alleged plot to unseat the king.
"He did say that he met with some of the tribal leaders, so one can then understand why the official view that this was a destabilizing move on his part", she said.