Pitt and Jolie played assassins in Mr and Mrs Smith

Jolie, a goodwill ambassador for the UN refugee agency, said they will be travelling to northern Pakistan within "a matter of days".

The actress has travelled to more than 20 countries for the agency since taking up the role in August 2001.

Millions have been left homeless by the 8 October earthquake, which killed more than 73,000 people in Pakistan.

The UN High Commissioner for Refugees (UNHCR) has flown tents and shelter material to help those left homeless by the disaster.

Jolie adopted her Cambodian son, Maddox, in 2002

Pitt joined Jolie at the UNHCR headquarters in Geneva on Tuesday for private briefings.

The pair, who starred together in Mr and Mrs Smith, have been romantically linked since Pitt split from his wife, actress Jennifer Aniston, in January.

UNHCR spokeswoman Jennifer Pagonis said the actress "takes her work for us extremely seriously and that means a lot to her and the staff".

Passport

"She's a terrific goodwill ambassador who can help people understand the difficult life of a refugee."

Meanwhile, Jolie - who adopted a Cambodian child, Maddox, in 2002 - has been given a Cambodian passport.

Her Maddox Jolie project campaigns for environmental reform and wildlife conservation in the country.

Interior ministry spokesman Khieu Sopheak said Jolie applied for the passport after she was granted citizenship in August this year.

Stephan Bognar, executive director of the Maddox Jolie project in Cambodia, said Jolie was "absolutely thrilled".

"Angelina has a very strong bond with Cambodia," he said