The Jordanian authorities also have good reason to be concerned about the Nahr al-Bared situation.

ECONOMIST: Is the Muslim Brotherhood turning its back on politics?

The population of 20, 000 doubled overnight when residents of the neighboring camp, Nahr al-Bared - under siege by the Lebanese army - fled their homes and moved in here.

NPR: Lebanon Standoff Highlights Refugees' Plight

Joined by hundreds of militants who flocked to Nahr al-Bared in recent months, very few of them Palestinian, the radical cult that calls itself Fatah al-Islam has vowed to fight here to the death.

ECONOMIST: Long the unluckiest of the lot

Nahr al-Bared's luck, it seems, has run out.

ECONOMIST: Long the unluckiest of the lot

Last year, a large number of heavily armed men surfaced at Nahr al-Bared, a Palestinian refugee camp on the edge of Tripoli in northern Lebanon, and took over bases belonging to a Syrian-backed Palestinian faction.

ECONOMIST: Syria and Lebanon

The references to Hamas and Nahr al-Bared reflect the Jordanian authorities' long-standing anxiety about being drawn into wider regional conflicts, a risk that is particularly acute in light of the large proportion of the population that is of Palestinian origin.

ECONOMIST: Is the Muslim Brotherhood turning its back on politics?

Many naturally turned to Nahr al-Bared.

ECONOMIST: Long the unluckiest of the lot

He went so far as to claim that some elements in the Brotherhood were seeking to drag Jordan into a situation similar to that in Nahr al-Bared, a Palestinian refugee camp in north Lebanon where the Lebanese army has been battling with heavily armed Islamist infiltrators for more than two months.

ECONOMIST: Is the Muslim Brotherhood turning its back on politics?

Under his command, Fatah al-Islam took over the Nahr el-Bared Palestinian refugee camp where it pinned down the Lebanese Army for four months before being overrun.

CENTERFORSECURITYPOLICY: George in jihadland