Britain's plan to ban khat, a leafy plant chewed as a stimulant in the Horn of Africa and the Arabian peninsula, should be dropped because it could alienate immigrants and damage counter-terrorism operations, MPs have said.
The British Parliament's Home Affairs Committee, a panel with influence but no legal power, said on Friday the ban was not based on any evidence of medical or social harm.
The government said in July that it would ban the drug, which is already prohibited in the United States and much of Europe, but parliament has yet to approve the decision.
We cannot afford for those who are already marginalised to be pushed towards criminality or extremism.
Banning the use of khat, or qat, would create tension between the police and immigrants, particularly Somalis who have settled across Britain, the committee said in a report.
It would also be seen as a betrayal by Kenya, where growing khat is a big source of income in some areas, the panel added.
Any damage to bilateral relations could undermine the two countries' joint fight against armed groups.
"It is baffling that potential friction, between already disadvantaged communities and the police, has not been fully considered," said committee chairman Keith Vaz.
"We cannot afford for those who are already marginalised to be pushed towards criminality or extremism."
Home Secretary (interior minister) Theresa May said in July that the ban would help prevent Britain from becoming a hub for the illegal trade in khat to countries where it is banned. She also cited evidence that khat has been linked to "low attainment and family breakdowns".
Kenyan lawmakers told the committee that a khat ban in Britain could lead to people once employed in the trade joining al-Shabab, an armed rebel group in Somalia.
The committee criticised the government for its failure to discuss the proposal in more detail with officials in Kenya, a former British colony.
"Considering Kenya's importance as a partner in the fight against international terrorism, and the well-established links between poverty and radicalisation, the lack of consultation on this issue is particularly concerning," the committee said.
Instead of a ban, the committee said the government should consider licensing khat imports to help prevent Britain becoming a hub for traffickers of the drug.