A court in Switzerland has found three Swiss engineers guilty of helping an international nuclear smuggling ring that supplied material and know-how to rogue states such as Muammar Qaddafi's Libya.

The Swiss Federal Criminal Court on Tuesday accepted the men's guilty pleas as part of a deal with prosecutors under which they will avoid further prison time but pay fines and legal costs.

Federal prosecutors said Urs Tinner, 46; his brother Marco, 43; and their 74-year-old father, Friedrich, had aided the nuclear smuggling network of Abdul Qadeer Khan between the late 1990s and 2003.

Prosecutors said the fact that the Tinners had cooperated with U.S. intelligence and thereby helped dismantle Khan's network counted in their favor. Khan is considered the architect of Pakistan's nuclear weapons program.