The Dutch government Tuesday banned the use of khat, a leaf native to East Africa chewed for its stimulant properties mainly by the Netherlands' sizeable Somali community.
"The drug khat is banned," the Dutch Immigration, Health and Justice departments said in a joint statement.
Khat is grown in the Horn of Africa and has for centuries been chewed by users in Ethiopia, Kenya, Somalia and Yemen.
"The problem lies especially within the Somali community, which is much larger than the Kenyan or Yemeni communities within our country," immigration department spokesman Frank Wassenaar told AFP, adding there were about 27,000 Somalis living in the Netherlands.
"If taken in moderation there are no major problems, but an investigation showed it to be problematic among some 10 percent of khat users," leading to health and social issues, added the statement.
An independent report commissioned by the Dutch government has cited noise, littering and groups of men who "roam the streets perceived as threatening", as some of the effects.
With high unemployment and low education levels, the Dutch Somali community was "late" in terms of integration, the report said.
Imported legally via Amsterdam's Schiphol airport four times a week, khat is distributed throughout the Netherlands but also in Germany, Sweden, Denmark and Norway, it added.
Around 843 tonnes of khat, worth a minimum 14 million euros (U$18 million) passed through Schiphol in 2010, up from 714 tonnes in 2009 and 693 tonnes in 2008.
Britain and the Netherlands currently allow the import, trade and consumption of khat, according to a European Monitoring Centre for Drugs and Drug Addiction letter of July last year entitled "Drugs in focus."
Fifteen of the European Union's 27 states and Norway list khat as an illegal narcotic, while in the other EU countries, the plant was not subjected to any controls, the EMCDDA letter said.