According to Ministry of Defence figures, France has supplied more than £2 billion-worth of military hardware to Ukraine, including anti-tank and missile systems.
The suspect, who is facing a range of terrorism-related charges, was born in the war-torn Donbas region of Ukraine, and is a Russian speaker.
Despite his injuries, he is cooperating with agents from the General Directorate of Internal Security (DGSI) – France’s equivalent of MI5.
His custody period ends on Friday, when magistrates will work out the next stage of the investigation.
He has claimed to investigators that he had built homemade batteries for mobile phones when one of them exploded.
On Thursday Russia detained a Frenchman working for a Geneva-based conflict mediation NGO, accusing him of gathering military information and failing to register as a “foreign agent”.
The surprise arrest prompted speculation that Moscow could be angling for a prisoner exchange for the former soldier held in France.
Nobody else was injured in the blast, and the B&B Hotel, which has more than 200 rooms, was evacuated and then closed.
Multiple security sources have confirmed that traces of TATP were found in his hotel room, together with batteries and barbecue lighters in plastic packages.
TATP was used by IS suicide bombers during the November 2015 attacks on Paris, which claimed 130 lives, and also by the Manchester Arena bomber in 2017, when 22 people were killed, and more than 1,000 wounded.
World leaders in France for D-Day anniversary
In regards to the current case in Paris, anti-terrorism prosecutors have opened an enquiry into “participation in a terrorist criminal association with a view to preparing crimes of attacks against persons, possession of an incendiary or explosive substance or product or of elements intended to compose an explosive device with a view to preparing destruction, and damage or harm to people, in connection with a terrorist enterprise”.
It comes as Volodymyr Zelensky, the Ukrainian president, joins other world leaders, including Joe Biden, the American president, and the King, for the D-Day 80th anniversary commemorations.
A massive security operation is accompanying their visit to Normandy, where they are guests of Emmanuel Macron, the French president.
The 2-star B&B tourist hotel has 226 air conditioned, non-smoking rooms and describes itself as a “cheap and well-located 24-hour check-in hotel”.
Its publicity states that it is “very close to the largest French and Parisian airport, so no more risk of missing your flight”.
The suspect is said to have arrived in France “very recently,” according to another investigating source, and had booked into the B&B Hotel under his own name.
He is now said to be recovering well from his wounds, and cooperating with officials.
Fears Russian agents plotting atrocities
Anti-terrorism prosecutors confirmed they have opened an investigation into “participation in a terrorist criminal association with a view to preparing crimes of attacks against persons, possession of an incendiary or explosive substance or product or of elements intended to compose an explosive device with a view to preparing destruction, and damage or harm to people, in connection with a terrorist enterprise”.
The man’s arrest follows Donald Tusk, the Polish prime minister, warning of Moscow-run agents plotting atrocities in Europe.
In May, nine people were arrested in Poland for allegedly preparing acts of sabotage in EU member states.
There have also been multiple allegations of Russian agents trying to “destabilise” France.
They are said to be behind an anti-Semitic graffiti campaign in the French capital which last month saw red “blood” hands painted on a Holocaust Memorial.
A similar cell has also been linked to other anti-Semitic campaigns, including the painting of blue Stars of David in other parts of the city last October.