Migrants' remittances reduce poverty in developing countries, but massive emigration of highly-skilled citizens poses troubling dilemmas for many smaller low-income countries, a new World Bank research study has found.

International Migration, Remittances and the Brain Drain, a study produced by the Bank's research department, includes a detailed analysis of household survey data in Mexico, Guatemala and the Philippines - all countries that produce millions of migrants - which concludes that families whose members include migrants living abroad have higher incomes than those with no migrants.

"The studies show that remittances reduce poverty and increase spending on education, health and investment," said World Bank economist Maurice Schiff, who co-edited the book with Caglar Ozden, also an economist at the Bank.

"The findings are consistent in all three country studies in this volume, and further studies are under way to see if they apply in other countries."