(CNN) -- African countries can raise up to $10 billion a year by tapping into the savings of nationals living abroad, leading economists have said.
A report released last week by the World Bank and the African Development Bank said sub-Saharan African countries such as Kenya, Nigeria and Ghana can potentially mobilize the wealth of their nationals scattered across the globe by issuing "diaspora bonds."
World Bank lead economist Dilip Ratha, the main author of the "Leveraging Migration for Africa: Remittances, Skills, and Investments" report, says there are about 30 million African migrants living outside their home countries, who are estimated to have more than $30 billion in annual savings.
Most of these savings are kept in bank accounts outside Africa or invested in migrants' host countries. "If a fraction of this money was tapped through diaspora bonds, then that could amount to $5-10 billion a year," says Ratha, pointing out that the figure is likely to be even higher.
"We don't know whether African diaspora members would only want to invest 10, 20 or 50% of their total savings," he says. "The estimate we've put together is an underestimate -- the true size of savings that diaspora members have is probably significantly larger."
Ratha says migrants' emotional ties with their home countries, coupled with attractive interest rates, can entice overseas communities to buy diaspora bonds.
"It's a patriotic discount in a way that one can tap into, plus the fact that diaspora members have lower risk perception about their country (than foreign investors) and better information," he says.
"Also, a more tangible benefit that they have, compared to the foreign investors, is that they do have local currency needs," he adds.
Diaspora bonds could provide a lifeline to countries struggling for access to capital and funds for infrastructure development, according to Ratha.
The practice of wooing wealthy migrants in high-income countries through bonds is not new. Israel and India have issued such bonds in the past, often in periods of financial difficulties, raising more than $35 billion.
Last year, debt-ridden Greece unveiled plans to raise up to $3 billion by targeting its wealthy communities abroad.
In Africa, a similar effort was launched by Ethiopia in 2009, although without much success, because of perceived political risk, according to Ratha.
He says there are several hurdles that need to be overcome for these bonds to be effective.
One problem is that the recognition of migrants as a resource for growth is relatively new in Africa. "There hasn't been a concerted and recognized effort to mobilize diaspora resources in any manner," Ratha explains.
Another difficulty is that a country issuing bonds must provide investors with extensive information, including transparency details and regular reports during the time that the bond is outstanding.
But perhaps the most significant obstacle is governance problems and the diaspora's perception of political risk in the country issuing bonds.
"That is a problem in many countries," Ratha says. "The minimum condition is, of course, the diaspora has to feel that there is enough credibility of the borrower on the other side and the money will be used properly and that the money will be paid back in the end."
But would migrants be interested in buying diaspora bonds if they were issued?
Joseph Alajemba, the general secretary of the National Association of Nigerian Communities in the UK, says diaspora bonds are a welcome idea, as long as the funds would be used to improve areas such as infrastructure and health care and are not mismanaged.
Alajemba, who lives in Cardiff, Wales, says: "If the money is going to be channeled into areas visible, that we can see, not just like the other type of money that comes in and is being hijacked from individuals, then definitely people would be willing to buy the bonds."
For Ghanaian Hannah Apeah-Kubi, who's been living in the UK for 29 years, diaspora bonds are a good idea that she says could help in the development of her country if they are purchased by enough people.
She says she would buy such a bond if she could "part with some money I wouldn't need immediately but can be put away for such purpose."
She adds: "The money locked away in the banks here, in foreign countries, can be used to develop Ghana."
In their report, the World Bank and the African Development Bank say that recorded remittances into Africa increased fourfold between 1990 and 2010, reaching almost $40 billion last year.
The report urges African governments to first strengthen and then maintain their links with their nationals abroad to realize the full economic benefits of migration.