Spain's parliament ratified the entry of Finland and Sweden to the North Atlantic Treaty Organization (NATO) on Thursday, bringing the two Nordic countries one step closer to joining the alliance in its most significant expansion since the 1990s as it responds to Russia's military campaign in Ukraine.

Sweden and Finland applied for membership in the 30-nation alliance in response to Russia's Feb. 24 actions. Russia has repeatedly warned both countries against joining the alliance and calls its actions in Ukraine "a special military operation."

NATO allies signed the accession protocol for the two countries in July. It must be ratified by the parliaments of all its members before Finland and Sweden can be protected by the defence clause. Following Spain's ratification, five countries remain on the list and ratification could take up to a year.

The lower house approved the accession with 290 votes in favour, 11 votes against and 47 abstentions.

"It is a historic result because we are consolidating NATO as an alliance of free and voluntary democracies that are united to defend peace," Sergio Gutierrez, lawmaker for the ruling Socialist Party said on Thursday.

(With input from Reuters)