By Katy Migiro

NAIROBI (Thomson Reuters Foundation) - Tens of thousands of children across southern Africa are being pushed out of school and into early marriage or child labor because of drought and hunger caused by the El Nino weather pattern, charities said on Wednesday.

Southern Africa has been hard hit over the past year by an El Nino-inspired drought that has wilted crops, slowed economic growth and driven food prices higher.

Increased numbers of children are trading sex and doing domestic work to survive across nine countries, a report by World Vision, the United Nations Children's Fund (UNICEF) and Plan International said.

"El Nino's impacts are worsening the lives of children in a number of areas with many facing sexual exploitation, violence, child labor and psychosocial distress," World Vision UK's child rights expert Tracy Shields said in a statement.

Children have become separated from their families as they leave home to find work or food, the report said.

More than 60 million people, two thirds of them in east and southern Africa, are facing food shortages because of droughts linked to El Nino, a warming of sea-surface temperatures in the Pacific Ocean, according to the United Nations.

The arrival of La Nina, a weather pattern which usually bringing floods to southern Africa, could worsen the situation, the U.N. has said.

Meteorologists predict a 50 to 75 percent chance of La Nina developing in the second half of this year.

Lesotho, Malawi, Namibia, Swaziland and Zimbabwe have declared national drought emergencies.

South Africa has declared a drought emergency in eight of the country's nine provinces, while Mozambique has declared an alert for some southern and central areas.

Southern Africa has a three-month window of opportunity before the 2016/2017 planting season, to take urgent measures to prevent millions of rural families becoming dependent on humanitarian assistance in 2018, the U.N. has said.

(Reporting by Katy Migiro; Editing by Alex Whiting; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women’s rights, trafficking, property rights and climate change. Visit to see more stories.)