Some 4m people were displaced during the 27-year war

Despite a surge in oil revenue, Human Rights Watch says only minimal health and education service are available to the hundreds of thousands of returnees.

Angola is one of Africa's largest oil and diamond exporters.

The government has not yet commented on the report, in which the UN is also criticised for reducing its presence.

"The government of Angola cannot afford to let its people down," Peter Takirambudde, executive director of HRW's Africa Division said.

Land mines

Some of the 4m people displaced in the brutal conflict, which ended three years ago, are returning to settle on heavily mined land, the report adds.

One woman, whose 20-year-old son lost half his leg in September picking mangoes, says children often play within yards of land mined areas.

"The problem is that people are hungry.

"The area was marked as mined but he was recently arrived and so hungry that he ignored the sign," she told HRW.

Funding cutbacks have forced the UN's World Food Programme to significantly reduce its food distribution.

"The United Nations should not abandon Angola in this critical moment," Mr Takirambudde said.

Corruption denial

In some parts of the country it claims authorities are harassing and sexually abusing returnees who do not have identity cards.

Much of Angola's infrastructure was devastated during the 27-year war, and the government says it lacks the resources to help returnees.

But as sub-Saharan Africa's second largest oil producer it is experiencing a windfall from high oil prices and has not adequately publicly accounted for those revenues, HRW says.

A supplier of crude oil to the US and China, Angola has denied allegations that revenues have been squandered through corruption and mismanagement.