By Mark Doyle BBC World Affairs Correspondent

The fast unfolding events in Ivory Coast have the potential to plunge the entire West African region into chaos.

What began as an army mutiny has resulted in parts of the north and centre of the country being taken over by rebels and become a region-wide crisis.

Ivory Coast lies at the economic and political crossroads of West Africa

Ivory Coast lies at the economic and political crossroads of West Africa with millions of foreign nationals basing themselves there.

If it becomes the centre of a regional power struggle, the possible consequences are dramatic.

The unthinkable

Until a few years ago the idea of Ivory Coast, a once stable country, being fought over by government and rebel forces, with foreign armies intervening to protect their various interests, would have been unthinkable.

But that is now the reality Ivory Coast citizens, and the foreigners living among them, must face.

Ivory Coast is home to five million foreigners

In the centre of the country, French and United States soldiers have evacuated their nationals while regional African powers weigh their options.

Burkina Faso, to the north of Ivory Coast, has been accused by the Ivorians of backing the rebels.

Although no evidence has yet been given to support this, Burkina Faso, a majority Muslim state, has tended in the past to be sympathetic to the mainly Muslim political opposition party in Ivory Coast.

Some other countries in the region, like Liberia on Ivory Coast's western flank, are so unstable that they could get dragged into cross-border activity irrespective of what the official Liberian position is.

Contingency plans

The West African region is already swirling with hundreds of thousands of refugees from earlier wars in Sierra Leone and Liberia.

Most of the foreigners living in Ivory Coast - some five million in all - are economic migrants.

But governments and aid agencies in the region have already begun contingency planning in case the fighting intensifies and some of them become refugees.