The Dutch government said it will ban qat, the narcotic plant used mostly by Ethiopian and Yemeni migrants, to curb its use and stop people re-exporting it to other European countries.

Amsterdam's Schiphol airport has become an import hub and clearing house for the green, leafy drug, which has a stimulating effect when chewed.

Last year more than 800 tons of qat were imported into the Netherlands, of which 80 percent was transported, mostly by car, to other European countries, including Germany, Denmark and Sweden, where it is banned, according to government estimates.

"Health Minister (Edith) Schippers will soon place qat on list II of the opium law. This will make possession and trade in qat illegal," said a joint statement from the Dutch interior affairs, security and justice and health ministries.

The plant, grown in the Horn of Africa and Yemen, is addictive and excessive use causes insomnia, stress, depression and apathy among users.

Sweden's police welcomed the move, saying authorities suspected profits from the qat trade were financing militant groups like al Shabaab in Somalia.

About 200 tonnes of qat was smuggled into Sweden a year, with a street value of 150 euros ($190) a kilo in Stockholm, Stefan Kalman from the Swedish police drug squad told Reuters.

"Smuggling to Scandinavia is quite substantial ... we catch smugglers on the Swedish border several times a week, though probably 9 in 10 transports get through," Kalman said.

"This ban means a huge change for us. I expect the numbers to go down now, as smuggling becomes more difficult," he added.

The Dutch government said social problems, including high unemployment in Somali communities in the Netherlands, prompted the ban.

Longstanding pressure from other countries to ban the drug was another reason, a government spokesman said.

The Dutch government has been clamping down on the sale of the soft drugs cannabis and hash since 2007 because of gang-related crime and concern about the risk to health. (Reuters)