Film star Angelina Jolie will use her powerful box office fame to draw attention to some of the world's worst humanitarian disasters, the U.N. refugee agency UNHCR said on Tuesday.

Jolie, who has already served more than 10 years as goodwill ambassador for the U.N. High Commissioner for Refugees (UNHCR), is taking on a new role as special envoy for large-scale crises that cause huge numbers of civilians to flee their homelands.

She is expected to concentrate on complex emergencies and protracted refugee crises including Afghanistan and Somalia which have driven millions of people into neighbouring countries, the UNHCR said.

"UNHCR is pleased to announce today that Angelina Jolie will take on a new and expanded role for the U.N. refugee agency as Special Envoy of High Commissioner Antonio Guterres," UNHCR spokesman Adrian Edwards told a news briefing in Geneva.

Jolie was due to be named Special Representative on the Afghan refugee crisis last October, but there has been no final agreement.

"In her new role, she is expected to focus on large-scale crises resulting in the mass displacement of people, to undertake advocacy and represent UNHCR and Mr. Guterres at the diplomatic level," Edwards added.

Jolie has already made 40 field visits to hotspots in 20 countries on behalf of the agency, including Pakistan, Haiti, Iraq, Syria and Chad. She has donated at least $5 million for its life-saving operations, Edwards said.

"This is an exceptional position reflecting an exceptional role she has played for us," he said.

Jolie and her longtime partner Brad Pitt, one of the world's best known couples, are engaged to marry, ending a fevered, seven-year celebrity media dance over whether they will ever say "I do".

A spokesman for Pitt confirmed last Friday that the pair had agreed to wed after Jolie was photographed in Los Angeles wearing a large diamond ring, designed by Pitt.
The couple, dubbed Brangelina by celebrity media, are raising six children together, three of whom are adopted.