A giant aquarium containing around 1,500 tropical fish burst in Berlin on Friday, flooding a hotel lobby and a nearby street and leaving two people injured, emergency services said.

It remains unclear what caused the incident at the 14-metre (26-foot) high AquaDom aquarium at around 5:50 am (0450 GMT), police said.

"A million litres of water and all the fish inside spilled onto the ground floor" of the hotel complex housing the aquarium, a spokesman for the Berlin fire department told AFP.

Two people suffered injuries from glass splinters and had to be hospitalised, the spokesman added.

More than 100 emergency workers were sent to the scene, which was scattered with glass and other debris.

The cylindrical AquaDom, which opened in 2004, was a popular tourist attraction in the German capital.

It is located in the foyer of a Radisson Blu hotel and had a clear-walled elevator built inside to be used by visitors to the Sea Life leisure complex.

According to the Sea Life website, the AquaDom is the largest cylindrical, freestanding aquarium in the world.

Frozen parrot fish

Berlin police said on Twitter that the incident had caused "incredible maritime damage" with the death of the hundreds of fish.

Water was also "massively" leaking onto the adjoining Karl Liebknecht Street, they said, forcing the partial closure of the major traffic artery. Tram service was also suspended.

The area around the complex was sealed off and sniffer dogs were being used to search for possible victims among the devastation.

Pictures and videos circulating online on Friday, apparently from guests staying at the hotel, showed extensive damage to the transparent aquarium, with only the frame still standing.

Bits of broken window panes and damaged furniture were scattered all around.

German lawmaker Sandra Weeser, who was staying at the hotel when the aquarium burst, said she was woken up by "a kind of shock wave".

"There was a slight tremor of the building and my first guess was an earthquake," she told the Berliner Morgenpost newspaper.

The area where the aquarium once stood was now just "dark and wet" she said, recalling how she saw "one of those large parrot fish lying on the ground, frozen".

The hotel has been evacuated and guests were offered shelter in heated buses amid freezing early morning temperatures, the fire service spokesman said.

A drone was being used to survey the extent of the destruction, he added.