German police Monday unleashed a massive crackdown on marijuana growers, raiding more than 200 gardens in an effort that involved police forces from 16 regional states and some 1,500 police investigators. There is no word yet on the number of arrests.

According to the Times of London, the trigger for the raids was the increasing popularity of a grow shop that has been selling equipment over the Internet. The paper reported that at least some of the raids were based on information drawn from the shops' customer lists.

But also arousing the concern of German authorities was what they described as increasing interest among Dutch marijuana traders in growing outside the Netherlands, where the conservative national government has been trying to move the country away from its decades-long policy of pragmatic tolerance of the herb.

"In the old days, hash farmers were almost always on the Dutch side of the border, but since the Netherlands got tougher we have been saddled with the problem," Ulrich Schulze of the Essen Customs and excise authority told the paper.

Although marijuana remains illegal in Germany, German police typically treat it with some tolerance, although that varies from state to state. German police are generally stretched to thin to control marijuana grows, Schulze said, but they could resort to using helicopters to look for outdoor grows. But most German grows are indoors.