Moscow is buzzing with rumours about what might have set off the latest crisis in the North Caucasus.

One popular theory is that it is a well-orchestrated conspiracy involving senior figures associated with the Kremlin.

The theory appears in various forms, but one version is that the media magnate and traditional Kremlin-backer, Boris Berezovsky has had recent meetings in Western Europe with Chechen warlord Shamil Basayev, the man said to be leading the insurgency in Dagestan.

Another version of the theory places presidential chief-of-staff Alexander Voloshin in a similar role.

According to this theory, the incursion of Chechen forces into Dagestan was provoked by the Kremlin itself, either as an excuse to call a state of emergency and postpone parliamentary elections due in December, or - in an even more elaborate theory - so that the new acting Prime Minister Vladimir Putin can prove himself by driving the insurgents back into Chechnya.

All this sounds far-fetched, the sort of conspiracy theory that is all too popular in Moscow, especially in opposition circles.

Holy war

There seems little doubt now that the incursion of Chechen-backed forces into Dagestan is a serious attempt by militant Islamic forces to broaden what they genuinely regard as a "Jihad" or holy war against the Russians, whom the militants see as infidels.

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The elected Chechen President, Aslan Maskhadov, says his government has nothing to do with it, and there is no reason to disbelieve him. But President Maskhadov has little control over some of his own militant leaders.

The main force behind the operation in Dagestan seems to be men who have long been a thorn in Maskhadov's side - Shamil Basayev, the Arab militant known as "Khattab" and, latest reports suggest, Salman Raduyev.

A spokesman for the regional Dagestani Government has said that the rebels' clear aim is to sweep down from the mountains and take over the whole of Dagestan.

This would certainly be a huge boost for the Chechens, giving them a friendly neighbour - the newly-proclaimed Islamic Republic of Dagestan - and access to the Caspian Sea and wider international links.

But if that is their aim, they are a long way from achieving it.

Differences with Chechnya

Dagestan may share some of the traditions of Chechnya - the Imam Shamil, who led the 19th Century resistance to Russia in the region, was a Dagestani, not a Chechen.

But Dagestan, with over 30 separate nationalities is different in many ways from ethnically homogenous Chechnya.

Unlike the Chechens, Dagestan's people were not deported from their homes by Stalin in the 1940s. The bitterness caused by that deportation, and the fierce desire for independence from Soviet Russia, were not nearly as strong as in they were Chechnya.

There is also bad feeling among some of the other nations against Chechens living in Dagestan, who came back in the 1950s to find their houses occupied by others.

In recent years, moreover, there have been a number of incidents in which the traditionally moderate Muslims of Dagestan have clashed with groups proclaiming a new brand of more militant Islam.