City councillors in Düsseldorf, capital of Germany's most populous state, are following Berlin in planning a pilot project in which cannabis could be sold legally to adults.

The move is the result of a joint push by the three parties which form the city's governing coalition, the Social Democratic Party (SPD), Greens and Free Democratic Party (FDP), the Frankfurter Allgemeine Zeitung reports.

The "traffic-light coalition" (red, green and yellow are the parties' respective colours) in the North Rhine-Westphalian capital came together on Wednesday to pass a plan providing for a strictly-regulated cannabis trade that would provide the drug to adults.

"Study, prevention and aid fall short because of criminalization," Green councillors Angela Hebeler and Norbert Czerwinski wrote on their party's blog on Thursday, adding that "the number of [cannabis] consumers fell drastically after it was decriminalized, for example in Portugal and the Netherlands."

"Controlled trade in cannabis products... opens up a possibility for...