With average economic growth of 5 per cent, Africa makes a lot of profit. The problem: a big chunk of the money doesn’t stay in the continent. Billions of African dollars are illegally transferred into foreign bank accounts every year, and effectively make the continent a net creditor, legal experts say.

Lawyers from some 40 bar associations and think-tanks from across the continent this week debated in Cameroon’s capital Yaounde how the leaks can be sealed. Over the past three decades, a staggering $1.4 trillion have left Africa in illicit financial flows, according to a joint study by the African Development Bank (AfDB) and US-based research group Global Financial Integrity (GFI).

That’s roughly equal to Africa’s current gross domestic product, twice as much as the development aid Africa received over 30 years and four times Africa’s current external debt.

“Africa loses about $50 billion every year to illicit financial flows,” said former Pan African Lawyers’ Association President Akere Muna. Most illicit transfers are the proceeds of corruption, laundering, mispricing, smuggling and tax evasion.

But money is also lost due to dubious but technically legal transactions, such as price manipulation or illegitimate contracts, Muna added. And then there is politics: numerous African leaders have become infamous for funnelling billions of illicit dollars into secret foreign bank accounts, draining their nations of crucial domestic resources.

Mobutu Sese Seko of Zaire — today the Democratic Republic of Congo (DRC) — allegedly siphoned away about $4 billion  during his 32 years in power, while Nigeria’s General Sani Abacha is accused of having stolen $2 billion  from state coffers, according to the United Nations Economic Commission for Africa.

Equatorial Guinea President Teodoro Obiang Mbasogo, who has been in power since 1979, reportedly funnelled $ 700 million to a bank in the United States. Contrary to common perception, however, money stolen by corrupt governments only makes up a small percentage of all illicit financial flows, says Global Financial Integrity president Raymond Baker.

The majority of illegal transfers, up to 65 per cent, are commercial transactions by multinational companies. In sub-Sahara Africa, Nigeria and South Africa are the biggest culprits, according to the AfDB-GIF report. Nigeria lost $142 billion between 2002 and 2012, while $100 billion  disappeared in South Africa over the same period.

Zimbabwe, Angola, DRC, Mauritius and Ivory Coast follow closely in terms of capital flight, according to watchdog Transparency International. But fingers should not be pointed at Africa alone, legal experts say. Foreign banks, who “provide a safe haven for looted wealth,” should be held accountable for accepting illicit funds, argued Nigerian lawyer and human rights activist Femi Falana.

Stricter international banking regulations were needed to help clamp down on illicit financial flows, as well as public registers for all cross-border transactions and improved litigation systems.

Former South African president Thabo Mbeki, who chairs the joint United Nations High Level Panel on illicit financial flows from Africa, called for a “radical strengthening” of state institutions to combat corruption. Former UN secretary general Kofi Annan, who heads the African

Progress Panel — a grouping of ten political and economic figures including former Nigerian president Olusegun Obasanjo, Nelson Mandela’s widow Graca Machel and activist musician Bob Geldof, called for a rule-based global system on tax transparency.

Tracking and prosecuting illegal money flow is complex, warned Anna

Garner, Executive Director of British non-profit International Lawyers for Africa.

“It requires a multi-jurisdictional and multi-disciplinary approach. You need lawyers, real estate experts, forensic accountants, bankers. There is a whole range of different disciplines that need to work together,” Garner explained.

Ultimately, the idea is to repatriate frozen funds to the African Development Bank, which would use the money for the region’s economic development.

But experts concede that, once illegal dollars have left Africa’s borders, the chances of returning illicit funds are slim. “The data (.) is often scanty, clouded in a mixed mass of information and scattered in disparate locations,” said Charles Goredema, researcher at South African think-tank Institute for Security Studies.

That leaves Africa with one immediate priority: Sealing the leaks.