It means authorities can impose exceptional measures, such as mandatory face masks.

Concerns had already rising among MEPs on whether holding the plenary session next week in France was too much of a risk, and whether it sends the right signal to EU citizens.

The parliament - in line with the EU treaty - needs to hold 12 plenary sessions in Strasbourg per year, even though MEPs have previously voted to scrap the costly monthly travel.

Preparations for the trip are currently ongoing, as the parliament decided in July to resume meetings in Strasbourg in September.

Parliament president David Sassoli is now to make the final decision ahead of the assembly's leadership and parliamentary group chairs meeting on Thursday (10 Thursday).

The leader of the Socialists and Democrats, Sassoli's group, Iratxe Garcia in a letter last week argued against going, saying that "threat of the pandemic is still very much present".

"Throughout Europe, we are asking our citizens to make sacrifices, to follow mitigating measures and to limit their movements, it is therefore impossible either to explain nor to justify why their representatives should increase the risk to counter these efforts," she wrote to Sassoli.

"The European parliament must lead by example and agree to hold the plenary in Brussels. Failing that, the Green group will limit its physical participation to the absolute minimum," co-chair of the Greens, Philip Lamberts said, The Green group historically supports dumping the Strasbourg seat altogether.

The liberal Renew group will discuss the issue at their meeting on Tuesday, while the centre-right European People's Party - whose MEPs are divided on the issue - will support Sassoli in his decision.

Parliament officials say the groups' positions are part of the many elements Sassoli is considering when deciding next week's meeting.

Sassoli is seeking out the advice of French authorities of the parliament's medical service, the European Centre for Disease Prevention and Control, which he needs to balance with the treaty requirement. Neglecting that could, in theory, prompt France to take the parliament to the European Court of Justice.

The "analysis is ongoing", a parliament spokesperson said, adding that "all [information] will be taken into account, but there is also the legal obligation".

"We know that it's going to be difficult," a parliament source described the dilemma, adding: "If the president decided not to go, the French will put pressure on him, but if we go and something happens, it will be president's responsibility."

"I will go to Strasbourg, and I will sit in my office to keep social distancing, like in Brussels" said the source.

Practicalities

Political groups sent a letter to the secretary general of the parliament, Klaus Welle, on Monday with questions about the specific arrangements in Strasbourg.

Next week's travel means that even with minimum staff, over a thousand people will make their way to the French city, with MEPs arriving from all over Europe.

Rooms in the parliament will be cleaned regularly, and there will be measures to make sure people can keep a safe distance - for example, extended hours at the canteen.

EU Commission president Ursula von der Leyen will also travel to Strasbourg to deliver her 'State of the EU' speech, launching the union's political season.