Parks have been chained up in Europe's most densely populated capital since the coronavirus lockdown began more than eight weeks ago.

Although parks have reopened in France's 'green zones' with fewer coronavirus cases, as a red zone Paris' parks remain closed, despite the city's mayor Anne Hidalgo pleading with the government to allow them to reopen if people wore masks.

But as temperatures hit 30C this week, an amateur lock-picker admitted that he has been opening parks at night to let Parisians sit on the grass and smell the roses.

Police clearing the laws of Les Invalides in Paris. Photo: AFP

A man calling himself “Jose” told French daily Le Parisien that he has been liberating parks in the poorer districts of northern and eastern Paris in a series of “Batman” style nocturnal actions.

Two handwritten posters hanging from the railings of the Parc de Belleville on Friday said “Thank you, Jose!”, seeming to show that the phantom locker picker has generated a following.

Discontent with the closure of parks has been rising since France began to slowly relax its lockdown last week, with the police forced to clear the huge open lawns in front of Les Invalides in central Paris of picnickers twice in two days.

Officers had earlier dispersed hundreds of people from the banks of Canal Saint-Martin.

Jose, who claims he only picks locks as a hobby and makes an honest living from a “normal job”, said: “Paris apartments are very small. We are supposed to be coming out of lockdown, but everything is closed.”

Almost a quarter of Paris's population escaped the city – many of them going to second homes in the country – during the strictest period of the lockdown.

But the city's poor and essential workers were stuck in often tiny flats during one of the sunniest springs on record.

Hidalgo, who is fighting a re-election campaign, asked the government to treat parks like the city's streets and allow people to “stroll through them if they were wearing a mask, which should be obligatory”.

But Health Minister Olivier Véran said the parks should stay shut as long as Paris and its surroundings remain in the “red zone” of infections.

He said the risk of people gathering and not respecting social distancing was too great.