Hamzah said he had been informed he was being punished for taking in part in meetings in which the king had been criticised, though he said he was not accused of joining in the criticism.
He then lashed out at the "ruling system" without mentioning the king by name, saying it had decided "that its personal interests, that its financial interests, that its corruption is more important than the lives and dignity and futures of the 10 million people that live here".
"I'm not part of any conspiracy or nefarious organisation or foreign-backed group, as is always the claim here for anyone who speaks out," he said. "There are members of this family who still love this country, who care for [its people] and will put them above all else."
"Apparently, that is a crime worthy of isolation, threats and now being cut off," he added.
Western allies on alert
It is rare for a senior member of the ruling family to express such harsh criticism of the Government, and any sign of instability in Jordan is likely to raise concerns among the country's Western allies.
Hamzah is a popular figure in Jordan. He is seen as religious and modest, in touch with the common people and similar to his beloved father, the late King Hussein. He has criticised the Government in the past, accusing officials of "failed management" after they approved an income tax law in 2018.
The country's top general had earlier denied that Hamzah was detained or under house arrest. Hamzah was asked to "stop some movements and activities that are being used to target Jordan's security and stability", General Yousef Huneiti was quoted as saying by the official Petra news agency.
He said an investigation was ongoing and its results would be made public "in a transparent and clear form".
"No one is above the law, and Jordan's security and stability are above all," he added.
Petra had earlier reported that Sharif Hassan bin Zaid, a member of the royal family, and Bassem Ibrahim Awadallah, a former head of the royal court, were detained. Awadallah also previously served as Planning Minister and Finance Minister and has private business interests throughout the Gulf region.
The agency did not provide further details or name the others who were arrested.
King 'has our full support' - US
Abdullah has ruled Jordan since the 1999 death of of his father, King Hussein, who ruled the country for close to a half-century. Abdullah has cultivated close relations with US and other Western leaders over the years, and Jordan was a key ally in the war against the Islamic State group. The country borders Israel, the occupied West Bank, Syria, Iraq and Saudi Arabia.
"We are closely following the reports and in touch with Jordanian officials," US State Department spokesman Ned Price said. "King Abdullah is a key partner of the United States, and he has our full support."
Saudi Arabia's official news agency said the kingdom "confirmed its full support to Jordan and its king and crown prince in all decisions and procedures to maintain security and stability and defuse any attempt to affect them".
Jordan's economy has been battered by the coronavirus pandemic. The country, with a population of around 10 million, also hosts more than 600,000 Syrian refugees.
Jordan made peace with Israel in 1994. The countries maintain close security ties, but relations have otherwise been tense in recent years, largely due to differences linked to Israel's conflict with the Palestinians.
Jordan is home to more than 2 million Palestinian refugees, most of whom have Jordanian citizenship. Israel's Foreign Ministry declined comment.
Jordan's stability a long-term concern
Stability in Jordan and the status of the king has long been a matter of concern, particularly during the Trump administration, which gave unprecedented support to Israel and sought to isolate the Palestinians, including by slashing funding for Palestinian refugees.
In early 2018, as then-president Donald Trump was threatening to cut aid to countries that did not support US policies, the administration boosted assistance to Jordan by more than US$1 billion over five years.
Abdullah stripped his half-brother Hamzah of his title as crown prince in 2004, saying he had decided to "free" him from the "constraints of the position" in order to allow him to take on other responsibilities. The move was seen at the time as part of Abdullah's consolidation of power five years after the succession.
The current crown prince is Abdullah's oldest son, Hussein, who is 26.
Jordan's ruling family traces its lineage back to Islam's Prophet Muhammad. Abdullah had chosen Hamzah as his crown prince hours after their father died of cancer in February 1999. The designation was out of respect for King Hussein, who was known to have favoured Hamzah the most among his 11 children from four marriages.
Until now, Abdullah and Hamzah have not displayed any open rivalry. In the videotaped statement, a portrait of King Hussein could be seen on the wall behind the prince.
