The Pope has said he plans to come, but nobody is entirely sure that he is serious. If he does, and if he encourages Christian pilgrims worldwide to meet him here, Israel (pop. six million, could be facing an influx of perhaps three or four million tourists.

The government's Israel 2000 committee, set up to promote millennium tourism and ensure that the state can cope with an unprecedented mass of arrivals, has gone through three directors in the past year, and has manifestly failed to ensure that Israel can cope with anything.

No agreement has been reached with the Palestinians about the smooth passage of visitors from Jerusalem to Palestinian-held Bethlehem. Seemingly trivial issues, such as the opening of a second exit at Jerusalem's Church of the Holy Sepulchre to prevent chaotic overcrowding, are still unresolved.

Muslims and Christians in Nazareth, a central pilgrim destination, are at loggerheads over the siting of a new mosque. Church leaders have threatened to mark the millennium by closing church doors throughout the Holy Land if no solution is found.

But while they struggle to prepare for the arrival of planeloads of harmless millennium tourists, the Israeli authorities' greatest fear is of the harmful visitors bent, not on the peaceful enjoyment of the country's holy sites, but on fomenting violence, on kick-starting the end of the world.

Even in years of no particular significance, Israel gets its share of religious eccentrics, people overcome by the power of history around them who become convinced that they are Moses, or Jesus, or the Virgin Mary, and insist on preaching loudly and publicly to this effect. Psychologists have a name for the phenomenon: Jerusalem Syndrome. It usually passes fairly rapidly.

But there have been cases of visitors overcome with religious fervour and driven to action: the Australian fundamentalist Christian, Michael Rohan, who set fire to the AlAqsa mosque in Jerusalem's Old City 30 years ago, or the American Jew, Alan Goodman, who opened fire on Temple Mount in 1982, killing one man, because "a divine command overpowered me".

Combine that context with the fact that various cults worldwide - such as Japan's Aum Shinrikyo - have already resorted to violence in a self-declared bid to bring about the Apocalypse, and that millions of "premillennialist" Christian evangelicals are convinced that the End of Days and Jesus's return are now precisely 2 1/2 months away, and you have a potent mix of bubbling expectation. And a major security headache.

To hear the Irish Ambassador, Mr Brendan Scannell, who spent most of last Sunday and Monday with the 25 Christians from Ireland who were refused entry to Israel at Haifa port, is to be persuaded that, in their case, Israel overreacted.

Last January the Israeli authorities threw out members of the Denver-based Concerned Christians cult, who had gathered at the behest of their leader, one Monte Kim Miller, to witness what he had assured them would be his death and resurrection in Jerusalem in December. Israeli investigators concluded that the cultists might resort to violence if Mr Miller's apocalyptic scenario did not unfold precisely to plan.

Initially, this week's Irish group was identified as a Concerned Christians offshoot. Later, Israeli police representatives could not even agree among themselves just who it was they were refusing to admit: an extreme cult, a group of potential suicides, or some pilgrims who did not have the necessary visas.

At the time of the Concerned Christians' deportation, the Israeli authorities made much play of the fact that they had set up an expert security task force to deal with potential incidents of millennium trouble. Quite apart from the awkward diplomatic fall-out from the case, its most worrying aspect is that, as the calendar rolls relentlessly forward, the confusion afflicting Israel's overall millennium preparations is evidently prevalent among the security authorities as well.