In another sign of growing anarchy in Gaza, the Strip’s border with Egypt has been closed after Palestinian police, backed by gunmen, imposed an armed blockade.European Union observers, who have been monitoring the crossing to assuage Israeli fears that foreign fighters and weapons could reach Palestinian militants, were forced to flee the area. The police are protesting over the killing of a colleague in a climate of spiralling internal violence since Israel withdrew from Gaza in September after 38 years of occupation. The crossing at Rafah was opened last month in a mive that was hailed as a step towards making Gaza a testing ground for Palestinian statehood. But the border standoff just adds to the troubles of officials already searching for British human rights activist Kate Burton and her parents who were abducted nearby on Wednesday. Concern is mounting as the Palestinian police chief admitted he did not know who the kidnappers were. It is not unusual for foreigners to be taken hostage in the area, but they are usually freed after a matter of hours.