The Central Bank of West African States (BCEAO), in Abidjan's busy business district, was robbed at around midday on Tuesday by men wearing suits.

BCEAO controls the issue of the CFA francs

Press reports claim it was an inside job organised by a security guard who allowed the robbers to drive into the grounds of the bank.

Police chief Desire Adjoussou said the country's borders were being sealed-off to stop the unknown number of robbers escaping.

Abidjan is the commercial hub of West Africa, with numerous international institutions based there.

But the country's first military coup two years ago has caused investors to flee and caused an economic slowdown.

The BCEAO issues the franc of the African Financial Community (CFA) which is the currency of Benin, Burkina Faso, Guinea Bissau, Côte d'Ivoire, Mali, Niger, Senegal and Togo.

Daylight robbery

Local newspaper, the Soir Info, headlined the raid as the "Hold-up of the Century" across a picture of the bank on its front page.

It also published a blurry black-and-white photograph of the security guard who allegedly aided the robbers.

A police official said security cameras had been tampered with before the robbery.

Local papers said the robbers stuffed 15 bags full of money into their car and then drove away with the security guard.

A spokeswoman for the bank said they were working closely with the judicial police but refused to give further details.

Officials from local retail banks were at the BCEAO when the robbery happened waiting for a security truck to take their monthly withdrawals to their branches.

The security truck arrived just before the robbery.