Southwark Council leader Peter John says the the fate of items in two galleries at the Cuming museum is 'unknown at present'.
Firefighters tackling the fire at Walworth Town Hall are currently damping down.
On twitter, Councillor John paid tribute to the London Fire Brigade and to Southwark Council for their efforts in trying to save the museum's collections.
Amazing work by LFB and Southwark Council museum staff to remove Cuming Museum artefacts from Walworth fire today.
More than a hundred firefighters have been trying to save a collection of artefacts from a blazing museum Credit: London SE1 websiteEmergency services were called to the building shortly before 12.30pm and 120 firefighters and 20 engines were on the scene Credit: London SE1 websiteIt is unclear how the fire started and no injuries have been reported, a London Fire Brigade spokesman said Credit: London SE1 website
More than a hundred firefighters have been trying to save a collection of artefacts from a blazing museum.
Firefighters evacuated 30 people from Cuming Museum and Newington library in Walworth, south-east London, after a fire took hold in the roof.
The museum, which was founded in 1906 with the Cuming family's private collection, is home to artefacts from all around the world, including objects from Roman London, Chinese ornaments and African tribal costumes.
It also contains a permanent exhibition on the history of Southwark.
It is unclear how the fire started and no injuries have been reported, a London Fire Brigade spokesman said.
Richard Rees, a 62-year-old pensioner who works in the community, said:
"When I got here the flames were going. The fire services arrived very quickly and did a fantastic job. All staff got out very quick and professional, they got out safe...It's a listed building, it was one of the very few treasured buildings in the community. It took a long time to get it listed and it is a very sad day for us.Parts of it are Grade I listed and parts Grade II. It is Victorian and was the old town hall before the big boroughs were set up. It is one of three in the borough which the council has been trying to sell off"
A fire service spokesman said the whole of the roof of the museum and library was on fire.
Station Manager Peter Critchell, at the scene, said:
"Flames are coming through the roof and there is thick grey smoke billowing up. Firefighters are still working hard at the scene to try and bring the blaze under control. We now have water jets attacking the fire from the four corners of the building. We evacuated 30 people from inside the museum and firefighters will be making efforts to salvage as many of the artefacts as possible."
– Peter Critchell, Station Manager, London Fire Brigade