BRUSSELS — The European Union’s Parliament is reviewing its files involving Qatar to see if any pressure was exerted on lawmakers, the assembly’s president said Thursday as a corruption scandal rocked the EU’s only directly elected institution.

Parliament President Roberta Metsola said the work under review includes an agreement to allow Qataris with biometric passports to have short visa-free stays in the EU. On Monday, the agreement was “sent back to committee for a full investigation,” she said.

Metsola said questions also have surfaced about a separate EU-Qatar air agreement on which the European Parliament must be consulted. Talks have started with the EU’s executive branch, the European Commission, to assess whether the accord should be suspended.

The agreement, signed in October 2021, would allow all EU airlines to operate direct flights to Qatar from any airport in the 27-nation bloc and give Qatari airlines the same access to European capitals. EU member countries have yet to approve it.

Metsola vowed that this would not be all. “We will look into everything. We will look into any undue pressure and any undue influence that we see that takes place,” she told reporters after talks with EU leaders in Brussels.

Belgian prosecutors have charged four people with corruption, participation in a criminal group and money laundering on suspicion of trying buy political favors at the parliament with money or gifts.

They include a former vice president of the European Parliament and her partner. Greek lawmaker Eva Kaili remains in custody awaiting a hearing on Dec. 22 and whose term in office was terminated by lawmakers this week. Her partner, Francesco Giorgi, who is a parliamentary advisor.

The heads of two charity groups have were charged. Pier Antonio Panzeri, head of the Fight Impunity campaign group and a former member of the EU parliament, and Niccolo Figa-Talamanca, secretary-general of another non-governmental organization, No Peace Without Justice.

Metsola promised sweeping reforms in coming months to crack down on corruption and influence peddling at the assembly.

Referring to the institution’s transparency register, she said: “yesterday, an NGO called No Peace Without Justice, which is allegedly connected to this investigation that is ongoing, which had 11 persons accredited on it, was suspended.”