BRUSSELS — The European Union’s parliament voted Thursday to suspend work on all files involving Qatar, and called for security passes for representatives of the Gulf country’s interests to be withdrawn until light can be shed on a corruption scandal rocking the assembly.

Rattled by a cash and gifts for political influence investigation that has ensnared four people so far, including a European Parliament vice president, the lawmakers committed to a tougher system of financial declarations and to ban donations from outside countries.

The commitments came in a resolution voted through in Strasbourg, France, by 541 in favor to two against, with three abstentions.

In Brussels, the assembly’s other main seat, 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. The agreement, she said, was “sent back to committee for a full investigation.”

Metsola said questions also have surfaced about a separate EU-Qatar air agreement on which the assembly 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 the 27 national leaders at an EU summit.

The scandal has unfolded as Qatar hosts the soccer World Cup. The small, energy-rich Arab Gulf nation has seen its international profile rise as Doha used its massive offshore natural gas fields to make the country one of the world’s richest per-capita. It has used that money to power its regional ambitions and win outsized influence on the international stage.

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

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

The heads of two charity groups were also charged: Giorgi’s former boss, Pier Antonio Panzeri, who leads the Fight Impunity campaign group and is a former member of the EU parliament, and Niccolo Figa-Talamanca, secretary-general of the non-governmental organization No Peace Without Justice.

Metsola promised sweeping reforms in coming months to crack down on influence peddling at the assembly. It would involve strengthening whistleblower protections, tougher policing of the code of conduct and an overhaul of the way the parliament deals with non-EU governments.

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.”

Asked whether any important legislative files, rather than non-binding resolutions, statements or texts of a purely political nature might have been influenced, Metsola said: “I have asked for a review of what has been voted on and worked on. I have no information in any way on that.”

German Greens EU parliamentarian Daniel Freund, a lead lawmaker on ethics, welcomed the commitment that his colleagues made to properly disclosing their financial assets.

“If it is possible to check whether assets correspond to transparent incomes or become inexplicably larger, this will deter corruption and make it more difficult to spend illegal money,” Freund said in a statement.

In a separate investigation on Thursday, the European chief prosecutor requested the lifting of Kaili’s parliamentary immunity due to possible fraud over the management of allowances that lawmakers receive and in particular related to the payment of parliamentary assistants.

The 44-year-old Greek former TV presenter was not protected by her parliamentary immunity in the corruption case because she was allegedly caught in the act.