Authorities had already reported the plot earlier this month, but the confessions shown on a prime time broadcast on Monday provided further details of the planned attacks.

The arrested men, who included Syrians, said they were ordered by Abu Musab al-Zarqawi, accused by Washington of being a top al-Qaida operative, to attack targets that included the heavily fortified US embassy and intelligence headquarters.

According to Aljazeera, security forces had shot dead those who refused to surrender. 

The head of the group, Azmi Jayusi, said he first met al-Zarqawi during his training in an al-Qaida camp in Afghanistan and met him again in Iraq, without giving any dates.

Security sources said al-Qaida had sought to punish Jordan for supporting Washington's efforts to pacify post-war Iraq and was incensed over covert aid Jordan had given to the US military campaign there.

Jordanian officials said they had found cars ten days ago carrying explosives that an underground group, believed to be linked to Usama bin Ladin's al-Qaida network, had set.

Jayusi said he planned the attack with trucks laden with 20 tonnes of explosives. King Abd Allah said after the arrest of the group earlier this month that the arrest had saved "thousands of lives".