At least two floors of Ivory Coast's multi-storey Treasury building were in flames on Tuesday as emergency services attempted to douse the fire and crowds formed nearby, according to a Reuters witness.

Officials were not immediately available to comment on the cause of the fire, which started at around 1200 GMT, when many employees were on their lunch break, or whether there were any injuries or deaths.

We went to eat and people called us to say that our building was on fire, said Aicha Kone, a treasury employee watching the fire with hundreds of others.

Ivory Coast, the world's top cocoa grower, has been in turmoil since a disputed November 28 election, with rival presidential claimants struggling for control of the West African country's coffers.

Incumbent leader Laurent Gbagbo has rejected international pressure to step down after U.N.-certified results showed he lost to rival Alassane Ouattara.

The regional Central Bank of West African States moved to cut Gbagbo off from Ivorian accounts in an attempt to loosen his grip on power, but Gbagbo late last month took control of the bank's local offices.

The crisis has led Ivory Coast to default on an interest payment for its $2.3 billion bond with Gbagbo's camp saying it will pay when creditors recognize him as president and Ouattara's camp saying it has no access to funds.

Ouattara's camp has called for a ban on cocoa exports to constrict Gbagbo's access to funds.