U.N. refugee agency special envoy Angelina Jolie on Sunday visited a camp for Syrian refugees in northern Iraq to drum up support for those displaced by years of civil war.

The Hollywood actress toured the Domiz camp, home to 33,000 refugees from Syria's seven-year conflict.

Jolie arrived in the morning and met families in the camp, a United Nations official said.

A day earlier she visited Mosul, Iraq's major northern city which Iraqi forces took back last year from Islamic State militants. The militants had occupied the city for three years and turned it into a stronghold of a "caliphate" in a military campaign that saw 900,000 residents flee.

Jolie met families from western Mosul and walked through bombed out streets, video footage and photos provided by the U.N. High Commissioner for Refugees (UNHCR) showed.

Normality has returned to many parts of Mosul, with displaced residents leaving camps nearby to return home.

But the Old City in West Mosul was largely destroyed during a campaign by a 100,000-strong alliance of Iraqi government units, Kurdish Peshmerga fighters and Shi'ite militias backed by air support from a U.S.-led coalition.

Reconstruction has been slow.

"This is the worst devastation I have seen in all my years working with UNHCR. People here have lost everything," Jolie said in a U.N. statement.

"They are destitute. They have no medicine for their children, and many have no running water or basic services," she said. "I hope there will be a continued commitment to rebuilding and stabilising the whole of the city. And I call on the international community not to forget Mosul."

Jolie has worked for UNHCR since 2001, visiting uprooted civilians from Iraq to Cambodia and Kenya. This is her fifth visit to Iraq, UNHCR said.