Austria, Germany, Denmark, Sweden and Norway, which instituted police checks due to the massive wave of migrations that started in 2015, must ensure that the measure is a last resort.

The European Commission had endorsed the three-month extension arguing that extraordinary circumstances which led to the reintroduction of the police checks still existed.

Slovenia, Greece, Slovakia and Hungary, which protect the south and east flank of the EU's external border, opposed the measure. Bulgaria, Cyprus and Poland abstained.

Slovenia also submitted a special statement arguing that the facts on the ground did not warrant the extension of checks.

"Slovenia is convinced the current circumstances no longer warrant a radical intervention in the fundamental values of the Schengen zone in the form of control on internal borders," the statement says.

Slovenia has been opposed to the extension effectively arguing that it is doing a good enough job protecting the external border, having erected a border fence and stepped up border controls.

It has also adopted legislation allowing it to affectively shut the borders tight to migrants in extraordinary circumstances; that measure was adopted with the argument that mass migrations remain a huge risk.