AMMAN: The half-brother and former heir of Jordan's King Abdullah, Prince Hamza, liaised with foreign parties over a plot to destabilise the country and has been under investigation for some time, the deputy prime minister said on Sunday.

On Saturday the military said it had issued a warning to the prince over actions targeting "security and stability" in the key US ally. Prince Hamza later said he was under house arrest. Several high-profile figures were also detained.

"The investigations had monitored interferences and communications with foreign parties over the right timing to destabilise Jordan," Ayman Safadi said in a televised news conference.

These included a foreign intelligence agency contacting Prince Hamza's wife to organise a plane for the couple to leave Jordan, he said.

"Initial investigations showed these activities and movements had reached a stage that directly affected the security and stability of the country, but his majesty decided it was best to talk directly to Prince Hamza, to deal with it within the family," he said.

Between 14 and 16 people had been arrested in connection with the plot, Safadi said.

Efforts were underway to resolve the crisis within the royal family, but Prince Hamza was not cooperative, he added. "It's a break from the traditions and values of the Hashemite family," Safadi said.

The developments are likely to rock Jordan's image as an island of stability in the turbulent Middle East. King Abdullah removed Prince Hamza from his position as heir to the throne in 2004, in a move that consolidated his power.