Up to 95% of the marijuana grown in the Netherlands is exported or consumed by foreign tourists, according to new justice ministry research.

This makes it pointless to regulate marijuana production for sale in licenced cannabis cafes within the Netherlands because illegal growing will continue, Opstelten said in a briefing to MPs.

The cabinet will not therefore meet demands made by big city mayors for some form of licenced growing, which, Opstelten said, would also conflict with international treaties.

The figures come from the government’s research centre WODC and are based on a complicated set of calculations, estimates and previous research.

The WODC estimates between 78% and 91% of marijuana grown in the Netherlands is exported. If the consumption by foreign tourists in the Netherlands is added to the total, then just 14% to 5% is consumed in the Netherlands by locals, the WODC says.

The government is under pressure to allow regulated production to supply the cafes and remove the grey area between licenced sales and illegal production.