Finland is the 20th of the EU's 27 countries that should ratify the treaty by 1 July 2013, when Croatia is scheduled to join the Union.
The ratification was supported by 131 deputies of the ruling coalition and part of the opposition, while 34 voted against.
Before the vote, Leko met with Parliament Speaker Eero Heinaluoma, who described the vote as historic. He said Finland and Croatia had enjoyed excellent relations for years, describing Croatia as a beautiful country of industrious people with approximately the same population as Finland. He said he saw the EU as a union of equals.
I hope that in the future, after Croatia joins, the voice of the small peoples will be heard in the EU, said Heinaluoma.
After the talks, Leko said Croatia and Finland were friends and partners, and that Finland believed Croatia was credible and on the right track. He said political cooperation between the two countries was good, especially on the parliamentary level.
Much more can be done on the economic front and in tourism, energy and science, said Leko.
He also held talks with the chair of the Finnish parliament's Grand Committee, Miapetra Kumpula-Natri. After the talks, he is scheduled to meet with the chair of the foreign policy committee, Timo Soini, Foreign Minister Erkki Tuomioja, and the Finnish-Croatian inter-parliamentary friendship group.
Croatia's Accession Treaty has not yet been ratified by Great Britain, Germany, France, Belgium, Denmark, the Netherlands, and Slovenia. In some countries, the procedure is nearing completion, such as in Great Britain, France and Belgium. The other countries will wait for the European Commission's final monitoring report due in March.
The Finnish ratification confirms the very good political relations with Croatia and its support for Croatia's EU accession. Finland played a very active role in the transformation processes in Croatia, participating in the modernisation of the legal system as well as in twinning projects.
About 30,000 Finnish tourists visit Croatia each year.
Former President Tarja Halonen visited Croatia in September 2009 and former Croatian Prime Minister Jadranka Kosor visited Finland in April 2010. Incumbent Croatian President Ivo Josipovic visited Finland in May 2011 and PM Zoran Milanovic in May 2012.
On that occasion, Milanovic and Finnish PM Jyrki Katainen spoke of the operations of the Finnish company Patria and suspicion of wrongdoing in its sale of combat vehicles to the Croatian military. They concluded this was a judicial and not a political issue. Katainen underlined the need to continue to reform the judiciary and improve the investment climate in Croatia.
Croatian Foreign Minister Vesna Pusic visited Helsinki in late November.