A Jordanian soldier was killed early Monday during a clash with militants along the Syrian border, the first Jordanian fatality linked to the current crisis, an official said.
A Jordanian security source said Corporal Mohammed Ali al-Manasir was killed in a shootout between border forces and a group of 16 armed militants attempting to enter the country from Syria.
He said four of the militants were killed and 12 others retreated into Syrian territory.
It was unclear whether the rebels were Jordanian or Syrian.
The clash occurred a few hours after Amman revealed that it had foiled a terror plot by 11 Jordanian extremists linked with al-Qaida in Iraq. They had allegedly plotted attacks against several Western embassies in the country.
According to the General Intelligence Department, the 11 suspects had travelled to Syria and smuggled automatic weapons, explosives and mortars back into the country.
Security sources could not confirm any link between the border clash and the arrests, but said both were likely related to the rising number of Islamist militants crossing into Syrian territory.
There is fresh concern over security along the 370-kilometer border of steep valleys and desert plains that officials say are prone to "black spots" utilized by smugglers to transport drugs, arms and fighters.
Alarm over the potential spillover of the Syrian crisis into Jordan and the security of Damascus's chemical weapons stockpiles has also led to increased presence of U.S., British and French forces and military advisors in the country, officials and diplomats said.