Angola has been warned to clean up its accounting of oil revenues in order to help rebuild its war-torn economy.

"The whole international community wants to see Angola move to better economic policies including transparency," said Walter Kansteiner, US assistant secretary of state for African Affairs.

The Angolan army and the Unita rebels signed a ceasefire agreement after 27 years of civil war earlier this month.

This has raised efforts to try and put Angola's economy, shattered by decades of civil war, into some sort of order and try to alleviate the widespread poverty.

Angola is rich in natural resources with both diamonds and oil - but exports have often been used to fuel the war.

It also has a fertile land for growing coffee and sugar cane. But since the country is littered with land mines, agriculture can be like Russian Roulette.

Missing money

The government is alleged to have used the smokescreen of war to hide its oil revenues.

The result has been that instead of the money helping development and poverty reduction, it has funded the armed forces and slipped into leaeders' bank accounts.

Mr Kansteiner says that the Angolan government must declare all its oil revenues onto its official budget.

"You're not going to get economic change or growth if you lose, say, 25% of your revenue strain," he said.

Angola is sub-Saharan Africa's second largest oil exporter, pumping about 900,000 barrels a day.

Global Witness, which specialises in the relationship between conflict and resource exploitation, believes that between a thrid and half of all state income - well over $1bn - went missing last year.

Time for change

Mr Kansteiner said the death of rebel fighter Jonas Savimbi could be a key turning point in the battle to restore economic order in Angola.

But the task ahead is daunting.

The war has left about four million of the former Portuguese colony's 12 million people displaced and killed around one million people.

The international monetary fund ceased lending to Angola in June 2001 because of the "missing" revenues.