European Commissioner for European Neighborhood Policy and Enlargement Johannes Hahn | Adem Altan/AFP/Getty Images Bosnia files EU membership application Commission calls for improved economic growth and rule of law reforms.

A quarter of a century after the war ended, Bosnia and Herzegovina formally applied to join the European Union Monday, the bloc's foreign policy chief said at a news conference in Brussels.

Federica Mogherini, the EU's high representative for foreign policy, praised the country, which is still reeling from a civil war in the 1990s, but said "a lot still needs to be done" for Bosnia to become an EU candidate state.

Areas in need of improvement include the rule of law, the economy, social justice and public administration, according to a joint statement by Mogherini and Johannes Hahn, the European commissioner for neighborhood and enlargement.

"We expect that the authorities at all levels will ensure that the challenges the country faces when it comes to its judicial system are addressed constructively," the joint-statement said.

The EU's 28 members and the European Commission will review the application and, if accepted, Bosnia will change from being a potential candidate to a candidate state.

Bosnia's application was "good news," Mogherini said, for the country and the EU, at a time when the 28-member bloc is facing economic and political challenges, including Britain's referendum on quitting the Union.

The fact that neighboring countries demonstrate "energy and willingness to join" the Union reminds members of the "responsibility we have also towards our European Union citizenship," she added.