Jordanian state television has aired what it says are confessions by captured militants tied to al Qaeda who said they had planned to launch deadly chemical attacks that could have caused thousands of deaths.
Authorities had already reported the plot earlier this month but the confessions shown on a prime time broadcast provided further details of the planned attacks.
The arrested militants who included Syrians said they were ordered by Abu Musab al-Zarqawi, accused by Washington of being a top al Qaeda supporter, to attack targets that included the heavily fortified U.S. embassy and intelligence headquarters.
The head of the group Azmi Jayousi shown confessing on Monday said he first met Zarqawi during his training in an al Qaeda camp in Afghanistan and met him again in Iraq without giving any dates.
Security sources said al Qaeda 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 U.S. military campaign there.
Jordanian officials said ten days ago they had found cars carrying explosives that an underground group believed to be linked to Osama bin Laden's al Qaeda network has set.
Jayousi said he planned the attack with trucks laden with 20 tonnes of explosives. King Abdullah said after the arrest of the group earlier this month that it had had saved "thousands of lives".
Jordanian intelligence officials have often boasted in recent years that their efforts have foiled plots by al Qaeda-linked militants to launch deadly attacks on Western targets and government installations.