(AP)—Swiss groups that aid people seeking to end their lives say they fear a national research program could lead to stricter rules for assisted suicide.

has long permitted "passive ," where someone can give another person the means to kill themselves provided the helper doesn't personally benefit from the death.

Dignitas, EXIT and EX International officials say a five-year government-funded study of people nearing the end of life is biased against assisted suicide and should be made more neutral.

The Swiss government dropped a plan to impose stricter rules in 2011, but the groups told reporters Thursday they fear the 15 million Swiss francs ($15.9 million) study could revive opposition to assisted suicide.

Study officials did not immediately respond to requests for comment.