Development of any site should be well organized in advance and include the participation of local people, a UN expert said Monday, which was World Habitat Day.
Cambodia has seen a huge influx of development projects, leading to the displacement of thousands of people, many of them unwillingly.
In some cases, those who are moved from an urban site have been living there illegally.
But Din Somethearith, the UN's World Habitat program manager in Cambodia, said Monday people should be considered during the plans of development, whether they occupy a space legally or not.
"There should be a good understanding, if you want to development a place, whether it will be in the interest of the people or the economy, whether people are living there illegally or legally, whether those people are supplemental for the growth of the economy or not," he said, as a guest on "Hello VOA."
Officials should not dismiss illegal residents out of hand, he said, as they also support the economy. Many people wish to live in urban areas because it provides a place for business, but by moving them out of town, a common practice across Phnom Penh development projects, a city loses their support.
Meanwhile, residents of a proposed development should be warned five years in advance, with opportunity for long discussions and problem-solving well ahead of time, Din Somethearith said.
The UN World Habitat project promotes higher living standards in Cambodia through partnership with the national government and local authorities.