The smoking ban introduced in the Netherlands from midnight last night is expected to have a damaging effect on the country's arcades and pubs market.

However, the café culture in the country has one unusual twist: the ban does not apply to cannabis.

The drug is legal in the Netherlands, and many cafés specialise in providing facilities for cannabis to be smoked.

However, the rule is that the cannabis must not be mixed with tobacco - and this may prove difficult to police.