"There is an urgent need for stronger cooperation between countries to make migration more safe and fair," said Thoraya Ahmed Obaid, head of the UN Population Fund (UNFPA). "And there is a dire need for greater action to address the lack of opportunities and human rights violations that lead many women to migrate in the first place," she added.

In its annual report on the state of world population, the UNFPA pointed out that nearly half the world's migrant population of 191 million were women. But the contribution they made to their home and host countries was largely ignored and their needs rarely met.

Human trafficking -- notably including the smuggling of women from poor countries to work as prostitutes in the rich West -- is the world's third-largest illicit trade after drugs and arms smuggling, the report noted.

Migration can also have damaging consequences in the developing world. The yearly exodus of 20,000 highly qualified nurses and doctors from Africa is worsening an already unprecedented health care crisis in region ravaged by HIV, malaria and high death rates.

One particularly vulnerable group is the army of migrant women who work as domestic servants for families in rich countries, the study noted. "Domestic workers are rarely protected by labour laws or allowed to organise. This leaves many dependent on employers for legal status, basic needs such as housing and food and the payment of due wages," it said.

"It also leaves them vulnerable to abuse. The report calls on governments to protect the rights of domestic workers."The UNFPA's focus on women migrants in this year's population report is designed to urge world leaders to address their needs during a special UN session on migration later this month.

"(This meeting) represents a critical opportunity to ensure that the needs and human rights of migrant women and their contribution to poverty reduction and development are explicitly and adequately recognised and addressed," the UNFPA said.

Ninety five million women have now left their home countries -- some in search of a better life, others forced to flee by conflict and persecution -- the report said.

These women send hundreds of millions of dollars back to their families and communities every year, helping the latter feed and educate their children, improve health care, build homes and support small businesses. In the receiving countries migrant women are such an integral part of society, particulary as nurses, child carers, domestic workers and cleaners, that their contribution goes virtually unnoticed, the report said.