It has been an EU member for six years, and now the Commission has given Croatia the greenlight to join the Schengen zone.

"It's an area that comes with freedoms and privileges but also with great responsibilities, joining this club is not something that we take lightly..." Greek Commissioner Dimitri Avramopoulos explained.

After four years of assessment the Commission says that Zagreb meets the necessary conditions to be part of the passport-free travel area. Countries joining must be able to ensure the security of the bloc's external border - a sensitive political topic due to migration since 2015.

"The future Schengen accession of Croatia, but also Bulgaria and Romania is all the more relevant and necessary given the migratory and security challenges of today," Avramopoulos said.

It is a sore point for Romania and Bulgaria - members since 2007, they have yet to be granted access to Schengen.

But the issue has also divided MEPS.

"For Croatia, it's not only some kind of satisfaction. It's some kind of commitment to even upgrade what is needed to overcome its problems," Croatian Socialist MEP Tonino Picula said.

"I'm disappointed. I think it's a political decision and I regret that we don't discuss it with the next Commission. Looking at the reality on the ground, we don't have a full Schengen functioning - this was a bad decision," Slovenian Socialist MEP Tanja Fajon explained.

It is now up to the EU national leaders to decide whether or not to let Croatia join the club.