By Mark Doyle BBC World Affairs correspondent

The government of Burkina Faso says it fears what it calls a "humanitarian catastrophe" in Ivory Coast where over two million Burkinabe citizens live.

The Ivory Coast government has indirectly accused Burkina Faso of backing rebels who have taken towns in the north of Ivory Coast near the Burkinabe border.

Gbagbo has hinted the rebels received foreign help

Burkina denies the charge, but says its expatriate citizens, who dominate the workforce on Ivorian cocoa and coffee plantations, are being targeted.

The Burkinabe statement reflects widespread concern in west Africa about the treatment of the large expatriate African population in Ivory Coast.

'Harassment'

A Burkina Faso government statement called for an immediate end to what it described as "the unacceptable harassment" of its citizens living in Ivory Coast.

It said that since the military uprising had begun, numerous Burkinabe had been killed by the Ivorian security forces or by Ivorian civilians who had, the statement says, "been incited by xenophobic hatred".

Burkina denies any involvement with the rebels

The Ivory Coast has a vibrant economy which, until the recent unrest, was a magnet for around five million African expatriates from countries like Burkina Faso, Mali, Nigeria and Ghana.

But at times of tension these foreign workers often suffer intimidation or worse.

The Ivory Coast Government has officially denounced Ivorian nationalists who have suggested expelling Burkinabe.

But there is still unease among West African leaders about the treatment of their nationals in Ivory Coast.

Ghana has said that some of its citizens are stranded by the fighting and that it is preparing to receive them back in Ghana if that becomes necessary.