If no new owner can be found to take on the park as a going concern then the animals will have to be dispersed to zoos in Britain and around the world - a difficult task which could take a year.
Chris Barlow, of receivers Cork Gully, who has been in charge of the park since January, said: 'It is no part of our strategy now or in the future to destroy animals.
'It is possible that very, very old or seriously ill animals, under veterinary advice, may have to be the subject of euthanasia.'
The park had been due to close next Sunday, but this was brought forward to yesterday after the receivers learnt that a Sunday newspaper was planning to announce the closure and report that it could become Britain's first Legoland - without any animals.
There were fears that animal liberationists could enter the park as paying visitors and stage a publicity stunt, or even try to rescue some animals in the belief that they were due to be destroyed. Police advice was sought.
The 144 acre (58ha) site in Windsor Great Park, which opened in 1970, went into receivership along with its owners, Themes International, which owed about pounds 40m.
It normally shuts for winter, but unless a buyer takes it on as a going concern it will not reopen next year.
Mr Barlow said if the animals had to be dispersed none would go to circuses or animal dealers and family groups would be kept together. The process would be vetted by 'an independent group of experts' whose chairman he declined to name.
The menagerie includes 34 lions, seven elephants, 45 baboons, seven tigers, 13 wolves and eight dolphins. The latter will have to be found new homes in any case because the receivers are not willing to spend the pounds 1m needed to bring the dolphin pools up to the standards demanded by new legislation.
Mr Barlow refused to be drawn on who might buy the park, but said discussions were continuing with several parties. The Danish toy giant Lego said it had been looking for a site for a second Legoland tourist attraction for some time, but would not say whether it had any interest in Windsor.
Visitor numbers at the safari park fell this year and the recession is making the task of selling the attraction harder. Themes International had spent about pounds 11m on upgrading the park and turning it into an 'African Experience' since buying it in 1988.