The discovery of asbestos at Auckland Museum is driving away tourists and causing a $2.5 million fall in income, Auckland councillors heard today.

The tourist hotspot was forced to close from May 10 after asbestos dust was detected in the museum’s original 1929 building and Grand Foyer. More asbestos was later identified in “additional areas of the building”.

The museum reopened in stages, 24 days after receiving clearance from a licensed asbestos assessor; however, the two most popular attractions, Te Marae Atea Māori Court and the Pacific galleries, remain closed.

Asked about revenue losses by councillor Richard Hill at today’s governing body meeting, the museum chief executive, David Reeves, said the 24-day closure led to a loss of about $500,000, and a further $2m drop in tourism income was budgeted in the current financial year.

The pataka (raised storehouse) in the Te Marae Atea Māori Court at Auckland Museum.

The financial hit was attributed to the loss of the Māori Court, leading to offering half-price entrance fees for international tourists, he said.

“When we briefly had it at full price, the push back was so enormous that we took the prudent decision to offer it at half price. Even so, we are seeing tourists walk away, which is incredibly sad.

“It’s a serious dent in our revenue,” Reeves said.

Last financial year, the museum earned about $3.3m from admission charges.

Reeves told councillors the source of the asbestos is in the Māori Court, where there are remnants of asbestos dust in the ceiling from a job in the late 1980s/early 1990s, which is being distributed around the building from a century-old ventilation system.

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He said the asbestos is extraordinarily hard to reach because there is a curved roof on top of a curved ceiling, and it is too small for a person to get into.

When fire alarms go off, it is believed that the massive smoke extraction fans are disturbing the asbestos dust and causing the problems, Reeves said.

Costumes in the Diva exhibition at Auckland Museum.

He said closing the gallery was affecting the museum’s tourism offer, but the southern two-thirds of the museum remained open, including the Diva exhibition from London’s Victoria & Albert Museum, featuring gowns by the likes of Rihanna and Lady Gaga.

The methodology for removing the asbestos, time and cost were still being worked out, said Reeves, who hoped the museum would have six galleries in the old building reopened by October.

Asked by councillor Chris Darby about the asbestos risk, Reeves said there had been nearly 2000 air tests for asbestos at the museum since May, and not one had shown a result above the WorkSafe limit for safe occupation.

“We are as confident as we can be, for our staff, our volunteers, our visitors, that in the areas of the building that are open, we have not presented an undue risk,” he said.