07/09/2016 10:11 PM AEST | Updated 08/09/2016 7:05 PM AEST

Paris Police Find Car Loaded With Gas Cylinders Near Notre Dame Cathedral

Authorities say the car’s owner is on a radicalization watchlist.

Charles Platiau / Reuters
The owner of a car parked near Notre Dame is on an intelligence services watchlist of people suspected of radicalization, authorities say. The owner was taken into custody but later released. 

PARIS (Reuters) - French police have arrested a second couple in connection with a car found carrying seven gas cylinders near Notre Dame cathedral in Paris, a judicial official said on Thursday.

The couple were arrested on Wednesday evening and taken into custody. Further details were not immediately available.

A first couple, aged 34 and 29, were arrested on a motorway on Tuesday in southern France also in connection with the incident on Saturday and remain in custody.

There was no detonating device present in the car, found on a Seine riverside stretch called the Quai de Montebello, yards from Notre Dame, one of Paris’s most popular attractions. Documents with writing in Arabic were also found in the car.

The car’s owner is on an intelligence services watchlist of people suspected of religious radicalization, police and judicial officials said on Wednesday. The owner was taken into custody but later released. 

The Peugeot 607, which had no registration plates, contained seven gas cylinders, one of them empty on the front passenger seat, two police officials said.

It was found with its hazard lights flashing, as if to attract attention, they said.

There was no detonating device present in the car.

More than 200 people have been killed in terror attacks over the past year-and-a-half in France.

France remains on maximum alert after calls by the Islamic State group for followers to attack the country, which is bombing the militant group’s bases in Iraq and Syria.

Florence Berthout, mayor of Paris’s Fifth Arrondissement (District), said on Wednesday the incident highlighted the need to beef up security and put more police on patrol in one of the world’s most visited cities.

She said the vehicle was left in a zone where parking is strictly prohibited and that it had remained there for around two hours before it came to the attention of police.

“Police and army staffing must be stepped up,” she told news TV channel BFM.

Thousands of extra police and soldiers have been deployed to patrol sensitive sites across France since 130 people were killed by Islamist gunmen and suicide bombers in multiple attacks on Paris last Nov 13.

A state of emergency declared at that time is still in place and gives police extra search and arrest powers but debate still rages over security levels, following a further attack on July 14 in which a man mowed into crowds in the city of Nice, killing 86.