See Rules of Procedure, section 43a: "Committee documents shall be secret if access to their contents would cause significant damage to the international relations of Finland or to the capital or financial markets. Likewise, documents shall be secret if they contain information on a business or professional secret or the state of health or financial status of a person, if access to that information would cause significant harm or damage and unless there is a pressing public interest requiring that the documents be public. A committee may decide, for a comparable compelling reason, that a given document is to be secret. Documents covered by the scope of discretion, as exercised by the Committee on the basis of section 50(3) of the Constitution, shall also be secret."
In addition, Section 24 of the Act on the Openness of Government Activities lists secret official documents (unfortunately, the translation of this act is not up to date).