Dutch prosecutors opened a criminal investigation Wednesday into an organization that supports members' efforts to buy a deadly powder to take their own lives.

The plan, announced last year by an organization called Cooperative Last Will, opened a new front in the long-running debate about and assisted in the Netherlands.

Prosecutors said in a statement they were launching their investigation "because assisting suicide is illegal" and because members of the organization were planning to place orders for the powder. The statement called on the organization to halt its activities.

Neither the group nor prosecutors have identified the powder. The group says it can be legally purchased.

In a response on its website, the organization denied wrongdoing and said its lawyers were studying the prosecutors' announcement.

While euthanasia has been decriminalized in the Netherlands if carried out by a physician who adheres to strict conditions, assisting suicide remains illegal.

The 2002 euthanasia law has done little to stem the debate in the Netherlands. One of the new frontiers for mercy killing advocates is a call to extend mercy killing to people who consider their lives to be completed but do not meet strict criteria for physician-administered euthanasia.

For years, advocates have called for drugs to be available that would allow people to end their own lives in a painless and dignified manner.

According to the country's statistics bureau, 1,894 people took their own lives in 2016. Meanwhile, euthanasia cases are on the rise, with 6,585 reported last year—4.4 percent of all deaths in the Netherlands.