Krefeld Zoo in Germany is to reopen today following the devastating fire in its Great Ape House during the New Year celebrations which killed all but two of its primate occupants.

An announcement on the zoo's website said that the chimpanzees Bally and Limbo both survived the fire, although slightly injured, and are being cared for by zoo veterinarians.

However, more than 30 animals lost their lives in the blaze, including five orang-utans, two gorillas, a chimpanzee, several monkeys and fruit bats and birds. The nearby Gorilla Garden did not catch light and the zoo reported that the gorilla Kidogo and six members of his family group are all still alive.

Police have said the accident may have been caused by a Chinese sky lantern, released as part of the celebrations, setting light to the plastic roof of the 2,000sq m (6,56ssq ft) monkey house. The use of sky lanterns is actually illegal in most parts of Germany, including Krefeld, and police have asked for witnesses to come forward.

Krefeld Zoo said the gutted ape house is in danger of collapse and has been cordoned off by police so that fire experts can investigate. It added that it was thankful for the "overwhelming wave of compassion and offers of help" it has received in the wake of the accident.

Describing the survival of the two chimps as "close to a miracle", zoo director Wolfgang Dressen said: "We have to seriously work through the mourning process. This is an unfathomable tragedy."