The spectacular theft of an estimated €88m (£77m) of crown jewels from the Louvre last month was “a deafening wake-up call” for the “wholly inadequate pace” of security upgrades at the Paris museum, the head of France’s state auditor has said.

Presenting the report, which was completed before the dramatic heist at the world’s most-visited museum, Pierre Moscovici said the Louvre had sufficient funds for the improvements and “must now implement them without fail”.

The court of auditors’ report said investments in maintenance and security were “indispensable for the long-term functioning of the institution”, but that the Louvre had consistently prioritised visible and attractive projects instead.

Pierre Moscovici discusses the heist. Photograph: Sarah Meyssonnier/Reuters

Four suspects are in custody over the robbery on 19 October, including three who are thought to have been members of the four-man gang who used a stolen truck with an extendable ladder and freight lift to reach the first-floor window of the museum’s Apollo gallery.

Two members of the gang smashed an unsecured window and two glass display cases before descending in the lift and fleeing on motorbikes driven by the other two, in a brazen daylight heist that lasted less than seven minutes from start to finish.

They fled with eight items, including an emerald and diamond necklace that Napoleon I gave to his second wife, Marie Louise, and a diadem set with 212 pearls and nearly 2,000 diamonds that once belonged to the wife of Napoleon III. None of the jewels have been recovered.

The report, covering the museum’s management between 2018 and 2024, concludes that decision-making had been “at the expense of the maintenance and renovation of buildings and technical facilities, particularly those related to safety and security”.

It also highlights a persistent delay in the deployment of security equipment for the protection of the artworks, saying the Louvre – which had more than 8.7 million visitors last year – had not addressed this failing during the period under review.

A security audit a decade ago, which found the museum was not sufficiently monitored or prepared for a crisis, only led to a tender for security work last year, the report says, and recommended upgrades would take a further eight years to complete.

It says only 39% of the rooms in the museum had been fitted with CCTV cameras as of 2024. “It will take several years to complete the project, which, according to the museum, is not expected to be finished until 2032,” the report says.

Jewels stolen from the Louvre. Composite: Louvre/Alamy

Excessive spending on artworks, only a quarter of which were on public display, wider management inefficiencies and ticket fraud had contributed to the museum’s inability to act on improving its security, it adds.

The report sets out 10 recommendations for management, including reducing the number of acquisitions and raising ticket prices.

The Louvre’s management said on Thursday it accepted “most” of the audit body’s recommendations.

An administrative inquiry into the theft that was completed last week reached similar conclusion, highlighting a “chronic, structural underestimation of the risk of intrusion and theft” and “an inadequate level of security measures”.

After complaints about the museum’s dysfunction, the Louvre launched an ambitious long-term development project in January, involving a new space dedicated to the Mona Lisa and new security measures.