The EU's former foreign policy chief Federica Mogherini has been charged along with two others in a probe into"fraud and corruption" over contracts to train future European diplomats, prosecutors said Wednesday.

Mogherini, who was high representative for foreign affairs from 2014 to 2019 and now leads the College of Europe graduate school, was arrested on Tuesday following raids at the elite school and on the premises of the EU's EEAS diplomatic service.

The 52-year-old Italian was detained for questioning along with the school's deputy rector as well as Stefano Sannino, a senior EU official who was secretary general of the European External Action Service from 2021 to 2024.

After being questioned by Belgian police,"the three individuals were formally notified of the accusations against them", said the European Public Prosecutor's Office (EPPO) which is overseeing the probe.

"The accusations concern procurement fraud and corruption, conflict of interest and violation of professional secrecy," it added in a statement.

Not considered a flight risk, all three were released from custody overnight, a spokesperson for the prosecutors' office said.

The EPPO is investigating suspicions of fraud related to an EU-funded training scheme for junior diplomats known as the European Union Diplomatic Academy.

The programme was awarded by the EEAS to the College of Europe in Belgium in the period 2021-2022, and the probe focuses on whether the tender process was skewed to favour the school.

Mogherini has headed the College of Europe since 2020, and in 2022 also took the helm of the EU Diplomatic Academy.

The contract involved was worth some €650,000 ($750,000), according to a European source.

Carried out by Belgian federal police at the EPPO's request, Tuesday's searches targeted the College of Europe campus in the Belgian city of Bruges, the Brussels premises of the EEAS and the houses of suspects.

The European Commission has confirmed raids at the EEAS, saying the probe focused on"activities that took place before in the previous mandate".

The current EU High Representative for Foreign Affairs Kaja Kallas took over the post a year ago from Mogherini's successor, Josep Borrell.

The College of Europe has vowed to"fully cooperate" with the probe, stressing its commitment"to the highest standards of integrity, fairness, and compliance – both in academic and administrative matters".

The EPPO is the independent public prosecution office of the EU, responsible for investigating crimes against the bloc's financial interests.

The probe, which is being led by a judge in Western Belgium, is also supported by the European Anti-Fraud Office (OLAF), to which the accusations were first reported.