The forcible eviction of 700,000 people from slums in Zimbabwe in 2005 was a crime against humanity, according to independent legal opinion
The human rights groups that sought the legal advice, say the issue could now be referred to the International Criminal Court in The Hague.
Zimbabwe's government called Operation Murambatsvina an urban clean-up campaign to remove illegal structures.
But the United Nations condemned the demolitions of shops and homes.
The Geneva-based Centre on Housing Rights and Evictions and another group, Zimbabwe Lawyers for Human Rights, sought independent legal opinion.
This concluded that the evictions in Zimbabwe were a widespread and systematic attack against a civilian population, as part of state policy.
"What happened in Zimbabwe was akin in magnitude to the Asian tsunami," Zimbabwean human rights lawyer Alec Muchadehma told reporters in The Hague.
The finding is that Operation Murambatsvina was a crime against humanity, and the UN Security Council therefore has authority to refer the matter to the International Criminal Court.
"We believe it is now time for the Security Council to take up this issue and we are calling on all 15 members ... to put it on the agenda and officially debate it," said Malcolm Langford, of the Geneva-based Centre on Housing Rights and Evictions.
The programme to build new homes to replace those demolished has faltered, says Amnesty International in its 2007 annual report.
"By May (2006) one year after the programmes launch, only 3,325 houses have been built, compared to 92,460 housing structures destroyed in Operation Murambatsvina," it said.
In recent years, millions of Zimbabweans have left the country as it grapples with runaway inflation, high unemployment and food shortages.
Lawyers say Zimbabwe evictions were crime against humanity, urge international prosecution
Corruption and poverty still rampant in Africa in 2006