Donations to fire-hit Chester Zoo have more than doubled the target after it was confirmed not all animals could be saved from the blaze that ripped through its rainforest attraction.

Over £100,000 was raised as public generosity saw the JustGiving appeal surpass the £50,000 target on Sunday to help fund the Monsoon Forest recovery from Saturday's fire.

Firefighters at Chester Zoo tackled the blaze on Saturday. Credit: PA

The rush of financial support came as the the zoo's chief operating officer confirmed insects, frogs, fish and small birds died on what he described as "one of the toughest days in Chester Zoo’s long history".

Jamie Christon also said the cause of the fire, which forced the zoo to close after a mass evacuation, is still not known.

The zoo had initially said all animals had been "accounted for" in the aftermath of the blaze, but brought sad confirmation of fatalities in its online Sunday statement.

Chester Zoo's chief operating officer Jamie Christon posted the message online on Sunday. Credit: Chester Zoo

In the message, posted on the zoo's website, Mr Christon said: "Keepers were able to encourage all mammal species away from the fire and to safety - including the zoo’s group of critically endangered Sumatran orangutans, Sulawesi macaques, endangered silvery gibbons and birds such as rhinoceros hornbills.

"We are though, devastated to say that we were unable to save some of our insects, frogs, fish and small birds who were located near to the outbreak of the fire. It’s absolutely heart-breaking to lose any animal, especially when conservationists have worked so hard to breed these wonderful species."

Mr Christon also paid tribute to the "remarkable efforts from the zoo team and the emergency services" which meant the fire was put out "as quickly as possible" and confirmed the moved animals had all been rehoused.

The zoo launched its £50,000 fundraising campaign after the fire destroyed much of the vast roof covering its Monsoon Forest area, which houses orangutans, gibbons, crocodiles, turtles and exotic birds.

The justgiving fundraising page had received more than £8,000 in donations by early Sunday before rocketing past the £50,000 target within hours.

A JustGiving page has been launched to support the recovery after fire. Credit: Chester Zoo/JustGiving/PA

The zoo confirmed earlier all mammals had been located in the hours after fire broke out, before keepers confirmed the fatalities among the birds, fish and amphibians.

Their artificial habitat was designed to mimic a south-east Asian environment.

The zoo, which partly reopened on Sunday, said it had been inundated with messages from people asking how they could lend their support.

“We remain committed to our mission to prevent extinction and for those who’re asking how they can help, we would welcome a donation to our continuing conservation work,” the zoo said.

Cheshire Fire and Rescue Service declared a major incident after it was called to the zoo shortly before 11.30am on Saturday.

Eyewitnesses described how visitors to the attraction – billed as the largest indoor zoo exhibit in the UK – were rushed to safety as the blaze spread rapidly through the polymer roofing material.

Meanwhile zoo staff led the animals housed in the structure to safety as firefighters arrived on the scene.

One person was treated for smoke inhalation as a result of the fire, according to North West Ambulance Service.

One eyewitness, David Clough, 50, who lives across the road from the zoo, said high winds fanned the flames in the roof of the building.

The fire as captured from across the road by a neighbour of the zoo. Credit: David Clough

He added: “We were very worried for the people and animals that would have been in the building.”

He added: “Orangutans and gibbons are our nearest neighbours there, but there are many other animals, including free-flying birds.”

A visitor, who declined to be named, told the Press Association: “We were in the monsoon enclosure when it happened and were rushed out due to an electrical fire. It spread very quickly.

“The staff ensured all the members of the public were safe. Many staff (were) running towards the fire, (I’m) assuming to help with evacuating animals.”