The online retailer closed its French centres Thursday in response to the ruling by a court outside Paris. It initially said it was closing for five days, during which period employees would be paid their full salaries.
The facilities are key in preparing orders submitted online for delivery to clients.
On Thursday Amazon France director general Frederic Duval said: “We will try to reopen as soon as possible, but I cannot today confirm the date.”
He told the RTL broadcaster the duration of the closure was “unknown”.
Amazon France’s biggest labour union, the SUD, took the company to court saying workers were being forced to work in close proximity in contravention of strict infection-busting social distancing measures announced by the government.
The court in Nanterre ruled that Amazon France had “failed to recognise its obligations regarding the security and health of its workers” and gave it a month to carry out an evaluation of the measures in place.
In the meantime, the company could continue deliveries of food as well as hygiene and medical products only, or risk a fine of one million euros ($1.08 million) for each day of non-compliance.
Amazon had said it was “perplexed” by the ruling as it had given the court evidence about temperature checks, physical distancing orders and use of personal protective equipment.
On Wednesday, a company committee voted to close the distribution centres to clean them and evaluate the health risks as ordered by the court.
“The labour action that led to this result will have big consequences for many people in France, for millions of clients who use our services to have products delivered to their homes during this confinement period, for our employees who will have to stay at home, for thousands of small and medium enterprises that use our services to do business by shipping via Amazon,” Duval said.
He added Amazon was confused by the court ruling.
“I do not know exactly how to define a hygiene product: are nail clippers among them? Is a condom a medical product?
“In these circumstances, taking into account the fine, we are compelled to close our sites,” said Duval.
France, like many other countries, has closed all non-essential businesses — only supermarkets and pharmacies are open in many areas.
Online retailers have continued to sell products now unavailable elsewhere, and in many countries Amazon has added thousands of staff to meet a surge in orders.