The spire tumbled to the ground in the fire that broke out on Tuesday morning, in scenes that shocked Denmark
The spire tumbled to the ground in the fire that broke out on Tuesday morning, in scenes that shocked Denmark AFP

Danish firefighters on Wednesday battled for a second day to extinguish a fire that gutted Copenhagen's historic former stock exchange, as police said an extensive investigation into the cause of the fire could last months.

Half of the 17th-century Borsen building was burned and its 54-metre (180-foot) spire tumbled to the ground in the fire that broke out on Tuesday morning, in scenes that shocked Denmark.

Emergency services announced the blaze was under control on Tuesday but it continued to burn in the part of the building, which had been undergoing renovation.

On Wednesday morning, firefighters were still tackling flames in the damaged part of the building, "where only the exterior walls remain", they wrote on X, the former Twitter.

They added they were working to secure the stability of the walls and monitoring undamaged areas. Firefighters predicted they would be battling the flames for another 24 hours.

Around 40 containers, each measuring 12 metres long, were being placed along the exterior walls of the burned part to support the structure walls, Frank Trier Mikkelsen, spokesman for Copenhagen's rescue service told news agency Ritzau.

"It is a complicated process and it can take several months before we can reach an answer," police said in a statement.

"For the time being we have carried out interviews, secured surveillance footage and carried out a series of investigative steps," Brian Belling, who is in charge of the investigation, was quoted saying.

Belling added a lot was still to be done, "especially since at this stage we have not yet had the opportunity to examine Borsen itself."

As one of the capital's oldest and best-known landmarks, the Borsen building also held a vast art collection and houses the Danish Chamber of Commerce.

Close to the Christiansborg parliament and seat of government, it was commissioned by King Christian IV and built between 1619 and 1640. It was the stock exchange until the 1970s.

In some positive news for Copenhagen's residents, Brian Mikkelsen, director of the Danish Chamber of Commerce said they had recovered the top of the building's iconic spire -- which was designed to look like it was made up of the intertwined tails of four dragons.

"It gave a glimmer of hope. Because it will once again adorn our beautiful workplace and Copenhagen," Mikkelsen said in a post to X.