The boss of Twycross Zoo says chimps were damaged by their appearance in TV adverts for tea.
Twycross Zoo has welcomed the birth of an endangered gorilla.
Endangered lemur twins have been moved to Twycross Zoo in an attempt to help the species breed.
Twycross Zoo was closed to the public after "some chimpanzees" got into an area where they should not have been.
A spokeswoman for Leicestershire Police said: "A call came in at 9.35am from the zoo to let us know that some chimpanzees, that were in the process of being moved from one building to another.
"In the process of this they have perhaps gone into an area of that building that they shouldn't have been in.
"They don't appear to have actually physically escaped. As a precaution, we've been called by the zoo."
The spokeswoman said they stopped people going into the park for a "short time", and added that there was no danger to anyone in the park and no animals were on the loose.
Twycross Zoo has re-opened following an 'animal incident'. It has not be confirmed what animal was involved.
We can confirm there has been an incident involving one of our animals. Twycross Zoo's team are working to... http://t.co/CYPFwjQZXS
A spokesperson for Twycross Zoo say they are dealing with an 'animal incident' on site and the zoo is currently closed to the public:
– Twycross Zoo
We're currently resolving an animal incident on site and the zoo will be closed to the public until further notice.
– Twycross Zoo
We can confirm there has been an incident involving one of our animals. Twycross Zoo's team are working to resolve the situation as quickly as possible, whilst ensuring the safety of the public and staff. The zoo is closed at present however we anticipate the zoo will reopen today and we will update you at 12 noon.
Thousands of people have flocked to Twycross Zoo for a family fun day in honour of its 50th anniversary.
The Summer Sundown Party, which is being held today and tomorrow, features live music, local traders in a vintage craft market and a 1960s themed school sports day.
Twycross Zoo is celebrating its 50th anniversary this weekend with their Summer Sundown Party. The two day event will include music from the Midlands, local traders in a vintage craft market and a 1960s themed school sports day.
Sharon Redrobe, Zoological Director, said: "On May 26th we entered into our 50th year and it seems only fitting that we mark this golden milestone with a summer celebration which will kick-start a year-long calendar of special events at the Zoo.
Dr Charlotte Macdonald, curator at Twycross Zoo said Louis' the chimp's long-time companion Choppers is "doing well" since his death.
She said Choppers "will be monitored closely" over the next few of weeks by the animal team, and introduced to other chimps in the near future.
Dr Macdonald said: "Although gone, Louis will never be forgotten; he will always be a member of our Twycross Zoo chimp family."
Louis was the star of the PG Tips adverts, even appearing as 007 in one of the ads.
The chimp who starred as 007 in the 1980s PG Tips advert has died, Twycross Zoo said.
Sharon Redrobe, Zoological Director at the zoo, said: "Over the decades millions of people would have visited Louis, so we hope people will join us in reliving old memories with him and take home some new ones of our other animals too."