The legislative reform was prompted by the government's concern Russia would try to influence Finland by organising large numbers of asylum-seekers to the border — something that happened at northern Finnish crossing points in 2015 and 2016 as Russian authorities reportedly ushered thousands of asylum-seekers there.
The risk of such hybrid threats from Moscow is seen as being particularly high now Finland has become an observer member of Nato, but not yet a full member enjoying the alliance's security guarantees, pending legislative approvals in all 30 member states.
Russia has repeatedly said over the past few years it is against Helsinki and Stockholm joining Nato. But both Finland and Sweden decided to seek membership in the alliance after Russia invaded Ukraine on February 24.
"The security situation in Finland and Europe has changed fundamentally in recent months, and especially the risk of a different kind of hybrid influence has increased," Finnish Justice Minister Anna-Maja Henriksson said in a statement.
"I'm glad that a new exception which covers hybrid threats, in particular, was added to the preparedness act so quickly with the broad support of the parliament," she said.
Following the ratification of Sweden and Finland's Nato membership by Canada, Denmark, Norway, Iceland and Estonia, the Albanian Parliament voted overwhelmingly in favour of welcoming the Nordic countries as new members of the alliance.
"Sweden and Finland are an added value to the alliance for their strategic and military values," Albania's foreign minister, Olta Xhacka, said in a speech to lawmakers.
"Their membership is a historic development that should be supported without any hesitation."