United Nations (New York), Dec 2 (IANS): Afghanistan's gross domestic product (GDP) likely will drop from $20 billion to $16 billion within a year, a 20 per cent plunge, the UN Development Programme (UNDP) has projected.

The agency warned in its Socio-Economic Outlook for Afghanistan that the economic base for the poorest country in Asia has long been, too, small to support its population of 40 million, Xinhua news agency reported.

"This new socio-economic assessment on Afghanistan estimates that restricting women from working could result in an immediate economic loss of up to $1 billion, or up to 5 per cent of the country's GDP," said UNDP Administrator Achim Steiner.

The UN body also warned that failing to invest in half of the country's human capital, girls' education, will have dire socio-economic consequences for years to come.

The economic modeling by UNDP and independent economists for the outlook indicated that with falling incomes and a growing population, it could take $2 billion to lift the incomes of all people in extreme poverty to the poverty line.