The Schengen Area allows free movement without the need for a passport or cross-border controls. But not all the states of the Union are included: Ireland, Cyprus, Croatia, Romania and Bulgaria remain, for various reasons, outside. While the area includes Switzerland, Liechtenstein, Norway and Iceland, which are not part of the EU.

Bulgaria and Romania in particular, which joined the Union in 2007, are patiently waiting to join and after more than a decade, the process has become a source of frustration for the governments in Sofia and Bucharest.

In fact, joining Schengen requires the application of common rules, adequate management of external borders, sharing of information on security and efficient police cooperation.

Romanians and Bulgarians insist they met the necessary criteria years ago. Last summer, they also joined the common Schengen visa scheme as "read-only participants", a formula that allows them to "accept" the entry of foreigners with a Schengen visa, but not issue their own.

But an obstacle remains, and it is of a political nature. The final green light must come from the Council of the European Union, which brings together the ministers of the 27 countries of the Union. The entry of a new Schengen member must be approved unanimously, which means that a single "no" can effectively freeze the whole process.

According to EU sources, in 2011 the dual candidacy was opposed by France, Germany, Finland, Sweden, the Netherlands and Belgium over concerns relating to corruption, organized crime and judicial reforms.

In the following years, the issue was repeatedly brought to the fore, only to be dismissed. The 2015 migration crisis further dampened Bulgarian and Romanian hopes of admission, but the tide may have changed with the Covid19 emergency.

At the moment Bulgaria and Romania remain included in the so-called cooperation and verification mechanism, a process started in 2007 which evaluates the introduction of reforms of the judicial system, the fight against corruption and, in the case of Bulgaria, money laundering.

The two countries are also the lowest-scoring EU members in the Corruption Perceptions Index published annually by Transparency International, although their results are not far off those of Hungary and Greece, two longtime Schengen members.