Jordan has complained about the treatment of its citizens in Syria.

The foreign minister, Abdel Ilah al-Khatib, said it was unacceptable for Jordanians to be detained or interrogated on arrival in Syria.

And he demanded information on five hundred Jordanians he said had been either detained or were missing in Syria.

His comments follow the detention for several hours of two Jordanian engineers at the border on Sunday while they were on their way to Lebanon.

Relations between the two neighbours have worsened since Jordan signed a peace treaty with Israel four years ago.