AKIPRESS.COM - Six Jordanian border guards were killed by a suicide bomber who drove a car at speed across the border from Syria and rammed it into a military post on Tuesday, security officials said, Reuters reports.

The explosives-laden vehicle blew up a few hundred metres from a camp for Syrian refugees in a remote, desolate area where the borders of Iraq, Syria and Jordan meet, a Jordanian army statement said.

The southeastern desert area is close to where Islamic State militants are known to operate, according to a security source who requested anonymity. The source said the attack appeared to be a well-planned military operation. No group has claimed responsibility.

The army said a number of other vehicles used in the attack at around 5:30 a.m. (0230 GMT) were destroyed and that 14 other people were wounded. The suicide bomber drove out from behind a berm and dodged gunfire to reach the military post, it added.

It was the first such assault targeting Jordan from Syria since Syria's descent into conflict in 2011 and followed an attack on June 6 on a security office near the Jordanian capital Amman in which five people, including three Jordanian intelligence officers, were killed.

The incidents have jolted the Arab kingdom, which has been relatively unscathed by the instability that has swept the Arab world since 2011, including the expansion of Islamic State in Syria and Iraq.

In a rare move, the Jordanian army's chief of staff declared the northern and northeastern border strip with Syria a closed military zone, an order that went into effect immediately.

"Any vehicle and personnel movement within these areas that move without prior coordination will be treated as enemy targets and dealt with firmly and without leniency," the army statement said.

International relief workers said the Jordanian authorities had also suspended all humanitarian aid to the area and that this could put the lives of refugees at risk.