A Belgian anti-nuclear group has lodged a complaint against NATO's military head, General Joseph Ralston, and Belgium's defence minister for allegedly violating the Nuclear Non-Proliferation Treaty.
"There is a treaty which prohibits the presence of nuclear weapons in Belgium and that treaty has been violated," Marcel Poznanski, spokesman for the NATO Alerts Network.
The complaint against US Air Force General Ralston and Belgian Defence Minister Andre Flahaut was filed on Saturday.
Poznanski referred to the Belgian Air Force base of Kleine Brogel in the east of Belgium where anti-nuclear activists believe US nuclear weapons are stored.
Poznanski said the international non-proliferation treaty stipulated that states with nuclear weapons should not transfer such weapons to states without them.
The 1970 treaty bars most states from acquiring nuclear arms and commits signatories that do possess them - Russia, China, Britain, France and the United States - to negotiate their elimination.
Poznanski said the public prosecutor would have to appoint an examining magistrate to look into the case.
A spokesman from the public prosecutor's office in the southern Belgian town of Mons, near NATO's military headquarters, was not immediately available for comment.
The air force base of Kleine Brogel has been the target of anti-nuclear demonstrations for several years.
NATO said last month that US Marine Corps General James Jones would replace Ralston as Supreme Allied Commander, Europe, (SACEUR) at a date to be determined.