A Dutch experiment involving the licenced production and sale of cannabis which is due to start this autumn is likely to be delayed, broadcaster NOS said on Thursday.

Arnhem mayor Ahmed Marcouch has told the city council that there are still many uncertainties that need to be ironed out and although a justice ministry spokesman did not use the word ‘delay’ he did point to the tough conditions surrounding the experiment, NOS said.

In total 10 cities, but not the big four, are taking part in the experiment which aims to remove the grey area between licenced cannabis cafes, or coffee shops, and the illegal drugs trade.

Independent research will assess the impact of having a closed chain from plantation to retail on crime and public order.

Marcouch said in his briefing that it was already clear in April when the 10 cities met ministry officials that not all the cities would be ready to participate in the autumn and that the start date of September/October would not be met.

In particular, the growers who have been selected to take part need more time to produce marijuana and hashish of the expected variety and quality, Marcouch said in his briefing.

According to the project outline, the 10 growers will all have to produce at least 10 different types of marijuana product and the thc content will have to be clearly marked on the packaging.

All coffee shops within each city’s boundaries must take part in the experiment, which will run for four years.