Christian Democratic Union (CDU) foreign policy spokesman Philipp Mißfelder told the Westdeutsche Allgemeine Zeitung (WAZ) that there was a "loophole" in the legal protections given to undercover agents.
They needed "the protection of the law, so that they won't be prosecuted for informants' crimes carried out to maintain their cover", he said.
The move follows a 2011 decision by a court in Düsseldorf, which found that there was no reason to stop the prosecution of a Federal Intelligence Agency (BND) informant from going ahead.
In such cases, the informant himself would be the main defendant and his secret service handler seen as an instigator.
Federal prosecutors released an opinion in April 2014 stating that there was insufficient legal protection for cases where informants were used.
Media reported at the time that the secret services were having trouble recruiting people to infiltrate terrorist cells.
Government sources told WAZ that a new law would be introduced sometime this year.
It is not yet known whether there will be a general amnesty or a list of what crimes informants are and are not allowed to commit in the line of duty.
Mißfelder also called for the secret services to be given more resources and authorization to spy on communications services including Skype and WhatsApp.