(Euthanasia campaigner Dr. Philip Nitschke poses for the photographer with his 'suicide kit' after a Reuters Interview in London May 7, 2009. REUTERS/Stefan Wermuth)

Right-to-die activists hope more countries will allow assisted suicide or euthanasia in coming years as the world population ages, but opponents are determined to stop them, a dispute that flared ahead of competing conferences in Switzerland.

“We have seen over the last 20 years a general migration of positivity towards this being a just cause,” Ted Goodwin, the American president of the World Federation of Right-to-Die Societies, told a news conference in Zurich on Tuesday.

Goodwin was speaking as representatives of 55 right-to-die societies from around the world gathered for a three-day congress to mark the 30th anniversary of Exit, a Swiss group which provides lethal drugs to help the terminally ill die.

Assisted suicide has been legal in Switzerland since 1942, if performed by a non-physician who has no direct interest in the death. Euthanasia, or “mercy killing”, is legal only in the Netherlands, Luxembourg, Belgium, and the U.S. state of Oregon.