The United Nations said the journey to camps in Kenya was long and perilous and many women and girls had allegedly been attacked by Somalia's Transitional Federal Government forces and allied militia in the country's south-central region.

“Once they cross the Somalia-Kenya border or reach Dadaab – the world's largest refugee settlement – their hopes of finding a safe haven are often overshadowed by new dangers and hardships, including the risk of rape,” UN Sexual Violence secretary general spokeswoman Margot Wallström said.

"I call on all parties to the conflict to immediately cease these gross violations of human rights."

Tens of thousands of people, including 29,000 children, have died in the famine.

An estimated 3.7 million people, almost half of them from Somalia, are at risk of famine.

Ms Wallström praised Kenyan authorities for their handling of the crisis so far, but urged more support from donors to relieve the famine and stop the attacks on vulnerable women and girls.

“There is an urgent need for services to be provided to survivors of sexual violence and for effective camp management to minimise the risks facing women and girls," she said.

"We should also improve monitoring and reporting on sexual violence to better inform our actions."

The Australian Government has donated $41 million for drought relief in the Horn of Africa.