Damascus, Syria—— The United Nations high commissioner for human rights called on Wednesday for Western countries to lift sanctions over Syria's years-long civil war after former leader Bashar al-Assad was ousted and went into exile.

During his visit to Syria, Volker Türk also pressed for transitional justice for victims, saying it had strengthened public trust in state institutions as the county made progress under de facto new leadership.

"Revenge and revenge are never the answer," Turk said, a month after rebel groups seized Damascus, ending the Assad family's decades-long dynasty.

Turk said he met with Ahmed Shallah, the leader of Tahrir al-Sham, the group leading the new regime in Syria. He said Shala assured him of the importance of respecting the human rights of all Syrians and said the authorities were committed to social cohesion and institutional reform.

The conflict in Syria erupted in early 2011, killing nearly half a million people and displacing millions, many of whom are now refugees. The war caused widespread damage that required tens of billions of dollars to rebuild.

"The Syrian people need as much help as possible to rebuild a state that works for all Syrians," Turk said, adding that Syria's territorial integrity, independence and sovereignty remain under threat and must be fully respected.

"The ongoing conflicts and hostilities must end," he said.

Soon after the conflict broke out, European countries and the United States imposed sanctions on Assad's government. They have been wary of the Islamic roots of the former rebels who now lead the interim government.

"It is crucial to bear in mind the impact of sanctions on the lives of the Syrian people," Turk said. "I therefore call for an urgent reconsideration of sectoral sanctions with a view to their lifting."

Also on Wednesday, Syrian Interior Ministry officials said authorities had detained an Egyptian militant who recently posted a video vowing to work to overthrow the Egyptian government.

Ahmed Mansour has lived in Syria for many years and was one of the fighters who overthrew Assad's government.

The foreign ministry official said on condition of anonymity that Mansour was detained late Tuesday because he was not authorized to speak to the media.

Mansour's arrest may ease concerns in some Arab countries, including Egypt, that Syria will not be used as a base for plots against countries in the region.