The report findings were handed over to Justice Minister Beatrice Ask.
The investigation focused on collaborative international efforts and on spying by refugees (flyktingspionage) from within Sweden.
The report proposed harder punishments for refugee spies, and said Swedish lawmakers should introduce a new criminal definition of "unlawful intelligence activities against a person" (olovlig underrättelseverksamhet mot person).
There have been several reports in Sweden of refugees reporting on the activities and allegiances of fellow refugees to the authorities in their country of origins, many of which punish political dissenters and in some cases their families.
On top of this, the investigators recommended that such a crime should carry a prison sentences rather than the fines that are given out in accordance with the existing laws.
The investigators added that it should be possible to arrest suspected spies earlier in an investigation than the current system allows.
The government appointed the investigation three years ago with the aim, according to Ask, to make it easier to catch those guilty of espionage in circumstances that extended beyond those affecting only national security.
The investigation, Ask said at the time, was to deal with information stretching beyond Sweden's military service.
Refugee spying has made headlines
Changes to the laws were proposed to come into effect on July 1st next year, with the fundamental changes to the constitution proposed to be amended by January 1st, 2015.